ORCID Profile
0000-0002-7422-9823
Current Organisation
University of Western Australia
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Astronomical and Space Sciences | Cosmology and Extragalactic Astronomy | Astronomical and Space Instrumentation | Photonics, Optoelectronics and Optical Communications | Galactic Astronomy |
Expanding Knowledge in the Physical Sciences | Scientific Instruments | Expanding Knowledge in Technology
Publisher: Oxford University Press (OUP)
Date: 19-02-2020
Abstract: We use the extended GALEX Arecibo SDSS Survey (xGASS) to quantify the relationship between atomic hydrogen (H i) reservoir and current star formation rate (SFR) for central disc galaxies. This is primarily motivated by recent claims for the existence, in this s le, of a large population of passive discs harbouring H i reservoirs as large as those observed in main-sequence galaxies. Across the stellar mass range 109 & M*/M⊙ & 1011, we practically find no passive (≳2σ below the star forming main sequence) disc galaxies with H i reservoirs comparable to those typical of star-forming systems. Even including H i non-detections at their upper limits, passive discs typically have ≥0.5 dex less H i than their active counterparts. We show that previous claims are due to the use of aperture-corrected SFR estimates from the MPA/JHU SDSS DR7 catalogue, which do not provide a fair representation of the global SFR of H i-rich galaxies with extended star-forming discs. Our findings confirm that the bulk of the passive disc population in the local Universe is H i-poor. These also imply that the reduction of star formation, even in central disc galaxies, has to be accompanied by a reduction in their H i reservoir.
Publisher: Oxford University Press (OUP)
Date: 13-01-2017
DOI: 10.1093/MNRAS/STX046
Publisher: Elsevier BV
Date: 08-2022
Publisher: American Astronomical Society
Date: 12-2007
DOI: 10.1086/516642
Publisher: EDP Sciences
Date: 07-2010
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 07-2016
DOI: 10.1097/NPT.0000000000000138
Abstract: Longitudinal information regarding the prevalence of upper limb somatosensory deficits and the association with motor impairment and activity limitations is scarce. The aim of this prospective cohort study was to map the extent and distribution of somatosensory deficits, and to determine associations over time between somatosensory deficits and motor impairment and activity limitations. We recruited 32 participants who were assessed 4 to 7 days after stroke, and reassessed at 6 months. Somatosensory measurements included the Erasmus-modified Nottingham sensory assessment (Em-NSA), perceptual threshold of touch, thumb finding test, 2-point discrimination, and stereognosis subscale of the NSA. Evaluation of motor impairment comprised the Fugl-Meyer assessment, Motricity Index, and Action Research Arm Test. In addition, at 6 months, activity limitation was determined using the adult assisting hand assessment stroke, the ABILHAND, and hand subscale of the Stroke Impact Scale. Somatosensory impairments were common, with 41% to 63% experiencing a deficit in one of the modalities within the first week and 3% to 50% at 6 months. In the acute phase, there were only very low associations between somatosensory and motor impairments ( r = 0.03-0.20), whereas at 6 months, low to moderate associations ( r = 0.32-0.69) were found for perceptual threshold of touch, thumb finding test, and stereognosis with motor impairment and activity limitations. Low associations ( r = 0.01-0.29) were found between somatosensory impairments in the acute phase and motor impairments and activity limitations at 6 months. : This study showed that somatosensory impairments are common and suggests that the association with upper limb motor and functional performance increases with time after stroke. Video Abstract available for more insights from the authors (see Supplemental Digital Content 1, links.lww.com/JNPT/A138).
Publisher: Elsevier BV
Date: 2020
DOI: 10.2139/SSRN.3608686
Publisher: Oxford University Press (OUP)
Date: 14-05-2020
Abstract: We investigate the stellar kinematics of the bulge and disk components in 826 galaxies with a wide range of morphology from the Sydney-AAO Multi-object Integral-field spectroscopy Galaxy Survey. The spatially resolved rotation velocity (V) and velocity dispersion (σ) of bulge and disk components have been simultaneously estimated using the penalized pixel fitting (ppxf) method with photometrically defined weights for the two components. We introduce a new subroutine of ppxf for dealing with degeneracy in the solutions. We show that the V and σ distributions in each galaxy can be reconstructed using the kinematics and weights of the bulge and disk components. The combination of two distinct components provides a consistent description of the major kinematic features of galaxies over a wide range of morphological types. We present Tully–Fisher and Faber–Jackson relations showing that the galaxy stellar mass scales with both V and σ for both components of all galaxy types. We find a tight Faber–Jackson relation even for the disk component. We show that the bulge and disk components are kinematically distinct: (1) the two components show scaling relations with similar slopes, but different intercepts (2) the spin parameter λR indicates bulges are pressure-dominated systems and disks are supported by rotation and (3) the bulge and disk components have, respectively, low and high values in intrinsic ellipticity. Our findings suggest that the relative contributions of the two components explain, at least to first order, the complex kinematic behaviour of galaxies.
Publisher: EDP Sciences
Date: 07-2010
Publisher: Springer Berlin Heidelberg
Date: 2007
Publisher: EDP Sciences
Date: 07-2010
Publisher: Oxford University Press (OUP)
Date: 25-11-2020
Abstract: We perform a joint analysis of high spatial resolution molecular gas and star-formation rate (SFR) maps in main-sequence star-forming galaxies experiencing galactic-scale outflows of ionized gas. Our aim is to understand the mechanism that determines which galaxies are able to launch these intense winds. We observed CO(1→0) at 1-arcsec resolution with ALMA in 16 edge-on galaxies, which also have 2-arcsec spatial-resolution optical integral field observations from the SAMI Galaxy Survey. Half the galaxies in the s le were previously identified as harbouring intense and large-scale outflows of ionized gas (‘outflow types’) and the rest serve as control galaxies. The data set is complemented by integrated CO(1→0) observations from the IRAM 30-m telescope to probe the total molecular gas reservoirs. We find that the galaxies powering outflows do not possess significantly different global gas fractions or star-formation efficiencies when compared with a control s le. However, the ALMA maps reveal that the molecular gas in the outflow-type galaxies is distributed more centrally than in the control galaxies. For our outflow-type objects, molecular gas and star-formation are largely confined within their inner effective radius (reff), whereas in the control s le, the distribution is more diffuse, extending far beyond reff. We infer that outflows in normal star-forming galaxies may be caused by dynamical mechanisms that drive molecular gas into their central regions, which can result in locally enhanced gas surface density and star-formation.
Publisher: Oxford University Press (OUP)
Date: 29-12-2019
Publisher: Oxford University Press (OUP)
Date: 15-04-2021
Abstract: Observations have revealed that disturbances in the cold neutral atomic hydrogen (H i) in galaxies are ubiquitous, but the reasons for these disturbances remain unclear. While some studies suggest that asymmetries in integrated H i spectra (global H i asymmetry) are higher in H i-rich systems, others claim that they are preferentially found in H i-poor galaxies. In this work, we utilize the Arecibo Legacy Fast ALFA (ALFALFA) and extended GALEX Arecibo SDSS Survey (xGASS) surveys, plus a s le of post-merger galaxies, to clarify the link between global H i asymmetry and the gas properties of galaxies. Focusing on star-forming galaxies in ALFALFA, we find that elevated global H i asymmetry is not associated with a change in the H i content of a galaxy, and that only the galaxies with the highest global H i asymmetry show a small increase in specific star formation rate (sSFR). However, we show that the lack of a trend with H i content is because ALFALFA misses the ‘gas-poor’ tail of the star-forming main-sequence. Using xGASS to obtain a s le of star-forming galaxies that is representative in both sSFR and H i content, we find that global H i asymmetric galaxies are typically more gas-poor than symmetric ones at fixed stellar mass, with no change in sSFR. Our results highlight the complexity of the connection between galaxy properties and global H i asymmetry. This is further confirmed by the fact that even post-merger galaxies show both symmetric and asymmetric H i spectra, demonstrating that merger activity does not always lead to an asymmetric global H i spectrum.
Publisher: Cambridge University Press (CUP)
Date: 06-2019
DOI: 10.1017/S174392131900913X
Abstract: We present an overview of recent key results from the SAMI Galaxy Survey on the build-up of mass and angular momentum in galaxies across morphology and environment. The SAMI Galaxy survey is a multi-object integral field spectroscopic survey and provides a wealth of spatially-resolved, two-dimensional stellar and gas measurements for galaxies of all morphological types, with high-precision due the stable spectral resolution of the AAOmega spectrograph. The s le size of ~3000 galaxies allows for iding the s le in bins of stellar mass, environment, and star-formation or morphology, whilst maintaining a statistical significant number of galaxies in each bin. By combining imaging, spatially resolved dynamics, and stellar population measurements, our result demonstrate the power of utilising integral field spectroscopy on a large s le of galaxies to further our understanding of physical processes involved in the build-up of stellar mass and angular momentum in galaxies.
Publisher: Elsevier BV
Date: 2016
Publisher: EDP Sciences
Date: 26-02-2004
Publisher: Cambridge University Press (CUP)
Date: 12-2010
DOI: 10.1017/S1743921311022976
Abstract: We are carrying out a multifrequency survey of late type galaxies in nearby clusters with the aim to investigate the effects exerted by both the very local and the global cluster environments. We report new VLA-HI images of galaxies in Abell 1367 and study the evolution of their gaseous component. In Abell 85 we perform a deep NIR imaging survey of the brightest spirals projected up to 1.0 Abell radius with the aim of unveiling possible gravitational effects on their stellar disks. Here we show preliminary results of these projects, mainly focused on infalling compact groups of galaxies moving towards their respective cluster centers.
Publisher: EDP Sciences
Date: 10-2015
Publisher: American Astronomical Society
Date: 30-09-2019
Publisher: American Astronomical Society
Date: 20-11-2005
DOI: 10.1086/496942
Publisher: Oxford University Press (OUP)
Date: 21-09-2013
Publisher: Oxford University Press (OUP)
Date: 24-10-2011
Publisher: Springer Science and Business Media LLC
Date: 2002
Publisher: Oxford University Press (OUP)
Date: 11-06-2009
Publisher: Oxford University Press (OUP)
Date: 13-01-2015
Publisher: Oxford University Press (OUP)
Date: 12-01-2017
DOI: 10.1093/MNRAS/STX053
Publisher: American Astronomical Society
Date: 09-10-2017
Publisher: EDP Sciences
Date: 03-2022
DOI: 10.1051/0004-6361/202142614
Abstract: We present the blind Westerbork Coma Survey probing the H I content of the Coma galaxy cluster with the Westerbork Synthesis Radio Telescope. The survey covers the inner ∼1 Mpc around the cluster centre, extending out to 1.5 Mpc towards the south-western NGC 4839 group. The survey probes the atomic gas in the entire Coma volume down to a sensitivity of ∼10 19 cm −2 and 10 8 M ⊙ . Combining automated source finding with source extraction at optical redshifts and visual verification, we obtained 40 H I detections of which 24 are new. Over half of the s le displays perturbed H I morphologies indicative of an ongoing interaction with the cluster environment. With the use of ancillary UV and mid-IR, data we measured their stellar masses and star formation rates and compared the H I properties to a set of field galaxies spanning a similar stellar mass and star formation rate range. We find that ∼75% of H I -selected Coma galaxies have simultaneously enhanced star formation rates (by ∼0.2 dex) and are H I deficient (by ∼0.5 dex) compared to field galaxies of the same stellar mass. According to our toy model, the simultaneous H I deficiency and enhanced star formation activity can be attributed to either H I stripping of already highly star forming galaxies on a very short timescale, while their H 2 content remains largely unaffected, or to H I stripping coupled to a temporary boost of the H I -to-H 2 conversion, causing a brief starburst phase triggered by ram pressure before eventually quenching the galaxy.
Publisher: Oxford University Press (OUP)
Date: 06-07-2016
Publisher: EDP Sciences
Date: 07-2012
Publisher: Oxford University Press (OUP)
Date: 26-05-2021
Abstract: Large galaxy s les from multiobject integral field spectroscopic (IFS) surveys now allow for a statistical analysis of the z ∼ 0 galaxy population using resolved kinematic measurements. However, the improvement in number statistics comes at a cost, with multiobject IFS survey more severely impacted by the effect of seeing and lower signal-to-noise ratio. We present an analysis of ∼1800 galaxies from the SAMI Galaxy Survey taking into account these effects. We investigate the spread and overlap in the kinematic distributions of the spin parameter proxy $\\lambda _{R_{\\rm {e}}}$ as a function of stellar mass and ellipticity εe. For SAMI data, the distributions of galaxies identified as regular and non-regular rotators with kinemetry show considerable overlap in the $\\lambda _{R_{\\rm {e}}}$–εe diagram. In contrast, visually classified galaxies (obvious and non-obvious rotators) are better separated in $\\lambda _{R_{\\rm {e}}}$ space, with less overlap of both distributions. Then, we use a Bayesian mixture model to analyse the observed $\\lambda _{R_{\\rm {e}}}$–log (M⋆/M⊙) distribution. By allowing the mixture probability to vary as a function of mass, we investigate whether the data are best fit with a single kinematic distribution or with two. Below log (M⋆/M⊙) ∼ 10.5, a single beta distribution is sufficient to fit the complete $\\lambda _{R_{\\rm {e}}}$ distribution, whereas a second beta distribution is required above log (M⋆/M⊙) ∼ 10.5 to account for a population of low-$\\lambda _{R_{\\rm {e}}}$ galaxies. While the Bayesian mixture model presents the cleanest separation of the two kinematic populations, we find the unique information provided by visual classification of galaxy kinematic maps should not be disregarded in future studies. Applied to mock-observations from different cosmological simulations, the mixture model also predicts bimodal $\\lambda _{R_{\\rm {e}}}$ distributions, albeit with different positions of the $\\lambda _{R_{\\rm {e}}}$ peaks. Our analysis validates the conclusions from previous, smaller IFS surveys, but also demonstrates the importance of using selection criteria for identifying different kinematic classes that are dictated by the quality and resolution of the observed or simulated data.
Publisher: EDP Sciences
Date: 07-2010
Publisher: Oxford University Press (OUP)
Date: 13-08-2015
Publisher: EDP Sciences
Date: 07-2010
Publisher: Oxford University Press (OUP)
Date: 29-01-2020
Abstract: We use H i and H2 global gas measurements of galaxies from xGASS and xCOLD GASS to investigate quenching paths of galaxies below the Star forming main sequence (SFMS). We show that the population of galaxies below the SFMS is not a 1:1 match with the population of galaxies below the H i and H2 gas fraction scaling relations. Some galaxies in the transition zone (TZ) 1σ below the SFMS can be as H i-rich as those in the SFMS, and have on average longer gas depletion time-scales. We find evidence for environmental quenching of satellites, but central galaxies in the TZ defy simple quenching pathways. Some of these so-called ‘quenched’ galaxies may still have significant gas reservoirs and be unlikely to deplete them any time soon. As such, a correct model of galaxy quenching cannot be inferred with star formation rate (or other optical observables) alone, but must include observations of the cold gas. We also find that internal structure (particularly, the spatial distribution of old and young stellar populations) plays a significant role in regulating the star formation of gas-rich isolated TZ galaxies, suggesting the importance of bulges in their evolution.
Publisher: Wiley
Date: 06-10-2023
DOI: 10.1002/CAM4.6573
Publisher: Oxford University Press (OUP)
Date: 26-05-2021
Abstract: We use comparisons between the Sydney-AAO Multi-object Integral Field Spectrograph (SAMI) Galaxy Survey and equilibrium galaxy models to infer the importance of disc fading in the transition of spirals into lenticular (S0) galaxies. The local S0 population has both higher photometric concentration and lower stellar spin than spiral galaxies of comparable mass and we test whether this separation can be accounted for by passive aging alone. We construct a suite of dynamically self-consistent galaxy models, with a bulge, disc, and halo using the galactics code. The dispersion-dominated bulge is given a uniformly old stellar population, while the disc is given a current star formation rate putting it on the main sequence, followed by sudden instantaneous quenching. We then generate mock observables (r-band images, stellar velocity, and dispersion maps) as a function of time since quenching for a range of bulge/total (B/T) mass ratios. The disc fading leads to a decline in measured spin as the bulge contribution becomes more dominant, and also leads to increased concentration. However, the quantitative changes observed after 5 Gyr of disc fading cannot account for all of the observed difference. We see similar results if we instead sub ide our SAMI Galaxy Survey s le by star formation (relative to the main sequence). We use EAGLE simulations to also take into account progenitor bias, using size evolution to infer quenching time. The EAGLE simulations suggest that the progenitors of current passive galaxies typically have slightly higher spin than present day star-forming disc galaxies of the same mass. As a result, progenitor bias moves the data further from the disc fading model scenario, implying that intrinsic dynamical evolution must be important in the transition from star-forming discs to passive discs.
Publisher: EDP Sciences
Date: 07-2010
Publisher: Oxford University Press (OUP)
Date: 11-12-2009
Publisher: Oxford University Press (OUP)
Date: 13-07-2023
Abstract: The connection between quenching mechanisms, which rapidly turn star-forming systems into quiescent, and the properties of the galaxy population remains difficult to discern. In this work we investigate the physical properties of MaNGA and SAMI galaxies at different stages of their star formation history. Specifically, we compare galaxies with signatures of recent quenching (Quenched) – $\\rm H \\, \\alpha$ in absorption and low Dn(4000) – with the rest of the low star-forming and active population (Retired and Ageing, respectively). The analysis is performed in terms of characteristics such as the total stellar mass, half-light radius, velocity-to-dispersion ratio, metallicity, and environment. We find that the Ageing population comprises a heterogeneous mixture of galaxies, preferentially late-type systems, with erse physical properties. Retired galaxies, formerly Ageing or Quenched systems, are dominated by early-type high-mass galaxies found both at low and dense environments. Most importantly, we find that recently quenched galaxies are consistent with a population of compact low-mass satellite systems, with higher metallicities than their Ageing analogues. We argue that this is compatible with being quenched after undergoing a star-burst phase induced by environmental processes (e.g. ram pressure). However, we also detect a non-negligible fraction of field central galaxies likely quenched by internal processes. This study highlights that, in order to constrain the mechanisms driving galaxy evolution, it is crucial to distinguish between old (Retired) and recently quenched galaxies, thus requiring at least two estimates of the specific star formation rate over different time-scales.
Publisher: Oxford University Press (OUP)
Date: 14-05-2021
Abstract: We present results from neutral atomic hydrogen (H i) observations of Hydra I, the first cluster observed by the Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY) on the Australian Square Kilometre Array Pathfinder. For the first time, we show that WALLABY can reach its final survey sensitivity. Leveraging the sensitivity, spatial resolution, and wide field of view of WALLABY, we identify a galaxy, ESO 501−G075, that lies near the virial radius of Hydra I and displays an H i tail. ESO 501−G075 shows a similar level of morphological asymmetry as another cluster member, which lies near the cluster centre and shows signs of experiencing ram pressure. We investigate possible environmental processes that could be responsible for producing the observed disturbance in the H i morphology of ESO 501−G075. We rule out tidal interactions, as ESO 501−G075 has no nearby neighbours within ∼0.34 Mpc. We use a simple model to determine that ram pressure can remove gas from the disc at radii r ≳ 25 kpc. We conclude that, as ESO 501−G075 has a typical H i mass compared to similar galaxies in the field and its morphology is compatible with a ram pressure scenario, ESO 501−G075 is likely recently infalling into the cluster and in the early stages of experiencing ram pressure.
Publisher: Oxford University Press (OUP)
Date: 29-11-2021
Abstract: The combination of gas-phase oxygen abundances and stellar metallicities can provide us with unique insights into the metal enrichment histories of galaxies. In this work, we compare the stellar and gas-phase metallicities measured within a 1Re aperture for a representative s le of 472 star-forming galaxies extracted from the SAMI Galaxy Survey. We confirm that the stellar and interstellar medium (ISM) metallicities are strongly correlated, with scatter ∼3 times smaller than that found in previous works, and that integrated stellar populations are generally more metal-poor than the ISM, especially in low-mass galaxies. The ratio between the two metallicities strongly correlates with several integrated galaxy properties including stellar mass, specific star formation rate, and a gravitational potential proxy. However, we show that these trends are primarily a consequence of: (a) the different star formation and metal enrichment histories of the galaxies, and (b) the fact that while stellar metallicities trace primarily iron enrichment, gas-phase metallicity indicators are calibrated to the enrichment of oxygen in the ISM. Indeed, once both metallicities are converted to the same ‘element base’ all of our trends become significantly weaker. Interestingly, the ratio of gas to stellar metallicity is always below the value expected for a simple closed-box model, which requires that outflows and inflows play an important role in the enrichment history across our entire stellar mass range. This work highlights the complex interplay between stellar and gas-phase metallicities and shows how care must be taken in comparing them to constrain models of galaxy formation and evolution.
Publisher: Oxford University Press (OUP)
Date: 12-2011
Publisher: Oxford University Press (OUP)
Date: 08-09-2017
Publisher: EDP Sciences
Date: 03-2012
Publisher: American Astronomical Society
Date: 21-07-2017
Publisher: American Astronomical Society
Date: 15-10-2018
Publisher: American Astronomical Society
Date: 13-08-2012
Publisher: EDP Sciences
Date: 09-2012
Publisher: EDP Sciences
Date: 02-2014
Publisher: Wiley
Date: 09-12-2009
Publisher: EDP Sciences
Date: 07-2018
DOI: 10.1051/0004-6361/201732410
Abstract: During pilot observations of the Virgo Environmental Survey Tracing Galaxy Evolution (VESTIGE), a blind narrow-band H α + [NII] imaging survey of the Virgo cluster carried out with MegaCam at the CFHT, we have observed the spiral galaxy NGC 4254 (M99). Deep H α + [NII] narrow-band and GALEX UV images reveal the presence of 60 compact (70–500 pc radius) star-forming regions up to ≃20 kpc outside the optical disc of the galaxy. These regions are located along a tail of HI gas stripped from the disc of the galaxy after a rapid gravitational encounter with another Virgo cluster member that simulations indicate occurred 280–750 Myr ago. We have combined the VESTIGE data with multifrequency data from the UV to the far-infrared to characterise the stellar populations of these regions and study the star formation process in an extreme environment such as the tails of stripped gas embedded in the hot intracluster medium. The colour, spectral energy distribution (SED), and linear size consistently indicate that these regions are coeval and have been formed after a single burst of star formation that occurred ≲100 Myr ago. These regions might become free floating objects within the cluster potential well, and be the local analogues of compact sources produced after the interaction of gas-rich systems that occurred during the early formation of clusters.
Publisher: EDP Sciences
Date: 07-2012
Publisher: EDP Sciences
Date: 02-2013
Publisher: Wiley
Date: 04-11-2009
Abstract: We are carrying out a programme of CO and interferometric H I observations in the nearby galaxy cluster Abell 1367. The aim is to better understand the processes driving the evolution of the ISM in late‐type galaxies in the cluster environment. Abell 1367 is a dynamically young cluster. We have determined the H I content and g – i colour from AGES (Cortese 2008) and SDSS, respectively, of its bright late‐type galaxies (spirals) in a volume centred on the NW subcluster. We use a combination of these characteristics, both of which are indicative of evolutionary history, to classify each spiral into one of four evolutionary states. This analysis revealed the cluster contains spirals in a wide range of evolutionary states. VLA D‐array imaging centred on the NW subcluster indicates most galaxies in that field have their H I intensity maximum offset relative to its optical counterpart, implying a recent and strong disturbance. The direction of this offset is not always consistent with a simple scenario of ram pressure stripping by the cluster's high density intra‐cluster medium (ICM) (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Publisher: Oxford University Press (OUP)
Date: 17-01-2022
Abstract: We present H i and radio continuum, narrow-band Hα imaging, IFU spectroscopy, and X-ray observations of the FGC 1287 triplet projected ∼1.8 Mpc west of the galaxy cluster Abell 1367. One triplet member, FGC 1287, displays an exceptionally long, 250 kpc H i tail and an unperturbed stellar disc which are the typical signatures of ram pressure stripping (RPS). To generate detectable RPS signatures the presence of an Intracluster medium ICM or intragroup medium IGM with sufficient density to produce RPS at a realistic velocity relative to the ICM or IGM is a prerequisite. However, XMM–Newton observations were not able to detect X-ray emission from the triplet, implying that if a hot ICM/IGM is present, its density, ne, is less than 2.6 × 10−5 cm−3. Higher resolution VLA H i data presented here show FGC 1287’s H i disc is truncated and significantly warped, whereas the H i tail is clumpy. TNG Hα imaging identified three star-forming clumps projected within 20 kpc of FGC 1287’s disc, with VIMOS–IFU data confirming two of these are counterparts to H i clumps in the tail. The triplet’s H i kinematics, together with Hα and radio continuum imaging suggests an interaction may have enhanced star formation in FGC 1287’s disc, but cannot readily account for the origin of the long H i tail. We consider several scenarios which might reconcile RPS with the non-detection of ICM or IGM X-ray emission but none of these unambiguously explains the origin of the long H i tail.
Publisher: EDP Sciences
Date: 06-2018
DOI: 10.1051/0004-6361/201732407
Abstract: The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) is a blind narrow-band (NB) Hα +[NII] imaging survey carried out with MegaCam at the Canada–France–Hawaii Telescope. The survey covers the whole Virgo cluster region from its core to one virial radius (104 deg 2 ). The sensitivity of the survey is of f ( Hα ) ~ 4 × 10 −17 erg s −1 cm −2 (5 σ detection limit) for point sources and Σ( Hα ) ~ 2 × 10 −18 erg s −1 cm −2 arcsec −2 (1 σ detection limit at 3 arcsec resolution) for extended sources, making VESTIGE the deepest and largest blind NB survey of a nearby cluster. This paper presents the survey in all its technical aspects, including the survey design, the observing strategy, the achieved sensitivity in both the NB Hα +[NII] and in the broad-band r filter used for the stellar continuum subtraction, the data reduction, calibration, and products, as well as its status after the first observing semester. We briefly describe the Hα properties of galaxies located in a 4 × 1 deg 2 strip in the core of the cluster north of M87, where several extended tails of ionised gas are detected. This paper also lists the main scientific motivations for VESTIGE, which include the study of the effects of the environment on galaxy evolution, the fate of the stripped gas in cluster objects, the star formation process in nearby galaxies of different type and stellar mass, the determination of the Hα luminosity function and of the Hα scaling relations down to ~10 6 M ⊙ stellar mass objects, and the reconstruction of the dynamical structure of the Virgo cluster. This unique set of data will also be used to study the HII luminosity function in hundreds of galaxies, the diffuse Hα +[NII] emission of the Milky Way at high Galactic latitude, and the properties of emission line galaxies at high redshift.
Publisher: EDP Sciences
Date: 07-2010
Publisher: Wiley
Date: 04-11-2009
Abstract: We have combined UV to radio centimetric observations of resolved galaxies in the Virgo cluster with multizone, chemospectrophotometric models of galaxy evolution especially tailored to take into account the effects of the cluster environment (ram pressure stripping and starvation). This exercise has shown that anemic spirals with truncated radial profiles of the gas component and of the young stellar populations, typical in rich clusters of galaxies, have been perturbed by a recent (∼100 Myr) ram pressure stripping event induced by their interaction with the cluster intergalactic medium. Starvation is not able to reproduce the observed truncated radial profiles. Both ram pressure and starvation induce a decrease of the stellar surface brightness of the perturbed disc, and thus can hardly be invoked to explain the formation of lenticular galaxies inhabiting rich clusters, which are characterised by higher surface brightnesses than early type spirals of similar luminosity. In dwarfs the ram pressure stripping event is so efficient to totally remove their gas thus stopping on short time scales ( Gyr) their star formation activity. Low luminosity star forming discs can be transformed in dE galaxies (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Publisher: EDP Sciences
Date: 07-2010
Publisher: EDP Sciences
Date: 22-06-2015
Publisher: Oxford University Press (OUP)
Date: 11-04-2010
Publisher: Oxford University Press (OUP)
Date: 05-07-2018
Publisher: Oxford University Press (OUP)
Date: 21-12-2013
DOI: 10.1093/MNRAS/STS376
Publisher: Springer Science and Business Media LLC
Date: 16-08-2022
DOI: 10.1007/S11357-022-00643-Y
Abstract: Healthy metabolic measures in humans are associated with longevity. Dysregulation leads to metabolic syndrome (MetS) and negative health outcomes. Recent exceptional longevity (EL) genome wide association studies have facilitated estimation of an in idual’s polygenic risk score (PRS) for EL. We tested the hypothesis that in iduals with high ELPRS have a low prevalence of MetS. Participants were from five cohorts of middle-aged to older adults. The primary analyses were performed in the UK Biobank (UKBB) ( n = 407,800, 40–69 years). Replication analyses were undertaken using three Australian studies: Hunter Community Study ( n = 2122, 55–85 years), Older Australian Twins Study ( n = 539, 65–90 years) and Sydney Memory and Ageing Study ( n = 925, 70–90 years), as well as the Swedish Gothenburg H70 Birth Cohort Studies ( n = 2273, 70–93 years). MetS was defined using established criteria. Regressions and meta-analyses were performed with the ELPRS and MetS and its components. Generally, MetS prevalence (22–30%) was higher in the older cohorts. In the UKBB, high EL polygenic risk was associated with lower MetS prevalence (OR = 0.94, p = 1.84 × 10 –42 ) and its components ( p 2.30 × 10 – 8 ). Meta-analyses of the replication cohorts showed nominal associations with MetS ( p = 0.028) and 3 MetS components ( p 0.05). This work suggests in iduals with a high polygenic risk for EL have a healthy metabolic profile promoting longevity.
Publisher: Oxford University Press (OUP)
Date: 09-2014
DOI: 10.2522/PTJ.20130271
Abstract: The association between somatosensory impairments and outcome after stroke remains unclear. The aim of this study was to systematically review the available literature on the relationship between somatosensory impairments in the upper limb and outcome after stroke. The electronic databases PubMed, CINAHL, EMBASE, Cochrane Library, PsycINFO, and Web of Science were systematically searched from inception until July 2013. Studies were included if adult patients with stroke (minimum n=10) were examined with reliable and valid measures of somatosensation in the upper limb to investigate the relationship with upper limb impairment, activity, and participation measures. Exclusion criteria included measures of somatosensation involving an overall score for upper and lower limb outcome and articles including only lower limb outcomes. Eligibility assessment, data extraction, and quality evaluation were completed by 2 independent reviewers. A cutoff score of ≥65% of the maximal quality score was used for further inclusion in this review. Six articles met all inclusion criteria. Two-point discrimination was shown to be predictive for upper limb dexterity, and somatosensory evoked potentials were shown to have predictive value in upper limb motor recovery. Proprioception was significantly correlated with perceived level of physical activity and social isolation and had some predictive value in functional movements of the upper limb. Finally, the combination of light touch and proprioception impairment was shown to be significantly related to upper limb motor recovery as well as handicap situations during activities of daily living. Heterogeneity of the included studies warrants caution when interpreting results. Large variation in results was found due to heterogeneity of the studies. However, somatosensory deficits were shown to have an important role in upper limb motor and functional performance after stroke.
Publisher: EDP Sciences
Date: 30-05-2012
Publisher: Oxford University Press (OUP)
Date: 05-06-2021
Abstract: The Deep Extragalactic VIsible Legacy Survey (DEVILS) is an ongoing high-completeness, deep spectroscopic survey of ∼60 000 galaxies to Y & 21.2 mag, over ∼6 deg2 in three well-studied deep extragalactic fields: D10 (COSMOS), D02 (XMMLSS), and D03 (ECDFS). Numerous DEVILS projects all require consistent, uniformly derived and state-of-the-art photometric data with which to measure galaxy properties. Existing photometric catalogues in these regions either use varied photometric measurement techniques for different facilities/wavelengths leading to inconsistencies, older imaging data and/or rely on source detection and photometry techniques with known problems. Here, we use the ProFound image analysis package and state-of-the-art imaging data sets (including Subaru-HSC, VST-VOICE, VISTA-VIDEO, and UltraVISTA-DR4) to derive matched-source photometry in 22 bands from the FUV to 500 $\\mu$m. This photometry is found to be consistent, or better, in colour analysis to previous approaches using fixed-size apertures (which are specifically tuned to derive colours), but produces superior total source photometry, essential for the derivation of stellar masses, star formation rates, star formation histories, etc. Our photometric catalogue is described in detail and, after internal DEVILS team projects, will be publicly released for use by the broader scientific community.
Publisher: American Astronomical Society
Date: 17-11-2016
Publisher: American Astronomical Society
Date: 25-08-2023
Abstract: Current methods of identifying the ionizing source of nebular emission in galaxies are well defined for the era of single-fiber spectroscopy, but still struggle to differentiate the complex and overlapping ionization sources in some galaxies. With the advent of integral field spectroscopy, the limits of these previous classification schemes are more apparent. We propose a new method for distinguishing the ionizing source in resolved galaxy spectra by use of a multidimensional diagnostic diagram that compares emission-line ratios with velocity dispersion on a spaxel-by-spaxel basis within a galaxy. This new method is tested using the Sydney-Australian-Astronomical-Observatory Multi-object Integral-Field Spectrograph Galaxy Survey (SAMI) Data Release 3 (DR3), which contains 3068 galaxies at z 0.12. Our results are released as ionization maps available alongside the SAMI DR3 public data. Our method accounts for a more erse range of ionization sources than the standard suite of emission-line diagnostics we find 1433 galaxies with a significant contribution from non-star-forming ionization using our improved method as compared to 316 galaxies identified using only emission-line ratio diagnostics. Within these galaxies, we further identify 886 galaxies hosting unique signatures inconsistent with standard ionization by H ii regions, active galactic nuclei, or shocks. These galaxies span a wide range of masses and morphological types and comprise a sizable portion of the galaxies used in our s le. With our revised method, we show that emission-line diagnostics alone do not adequately differentiate the multiple ways to ionize gas within a galaxy.
Publisher: Oxford University Press (OUP)
Date: 11-2008
Publisher: Springer Science and Business Media LLC
Date: 10-2008
DOI: 10.1038/NATURE07366
Abstract: Galaxies are complex systems the evolution of which apparently results from the interplay of dynamics, star formation, chemical enrichment and feedback from supernova explosions and supermassive black holes. The hierarchical theory of galaxy formation holds that galaxies are assembled from smaller pieces, through numerous mergers of cold dark matter. The properties of an in idual galaxy should be controlled by six independent parameters including mass, angular momentum, baryon fraction, age and size, as well as by the accidents of its recent haphazard merger history. Here we report that a s le of galaxies that were first detected through their neutral hydrogen radio-frequency emission, and are thus free from optical selection effects, shows five independent correlations among six independent observables, despite having a wide range of properties. This implies that the structure of these galaxies must be controlled by a single parameter, although we cannot identify this parameter from our data set. Such a degree of organization appears to be at odds with hierarchical galaxy formation, a central tenet of the cold dark matter model in cosmology.
Publisher: Oxford University Press (OUP)
Date: 27-07-2022
Abstract: Using the eagle (Evolution and Assembly of GaLaxies and their Environments) suite of simulations, we demonstrate that both cold gas stripping and starvation of gas inflow play an important role in quenching satellite galaxies across a range of stellar and halo masses, M⋆ and M200. Quantifying the balance between gas inflows, outflows, and star formation rates, we show that even at z = 2, only $\\approx 30{{\\ \\rm per\\ cent}}$ of satellite galaxies are able to maintain equilibrium or grow their reservoir of cool gas – compared to $\\approx 50{{\\ \\rm per\\ cent}}$ of central galaxies at this redshift. We find that the number of orbits completed by a satellite on first-infall to a group environment is a very good predictor of its quenching, even more so than the time since infall. On average, we show that intermediate-mass satellites with M⋆ between will be quenched at $10^{9}\\, {\\rm M}_{\\odot }\\, {\\rm and}\\, 10^{10}\\, {\\rm M}_{\\odot }$ first pericenter in massive group environments, $M_{200}\\gt 10^{13.5}\\, {\\rm M}_{\\odot }$ and will be quenched at second pericenter in less massive group environments, $M_{200}\\lt 10^{13.5}\\, {\\rm M}_{\\odot }$. On average, more massive satellites ($M_{\\star }\\gt 10^{10}\\, {\\rm M}_{\\odot }$) experience longer depletion time-scales, being quenched between first and second pericenters in massive groups, while in smaller group environments, just $\\approx 30{{\\ \\rm per\\ cent}}$ will be quenched even after two orbits. Our results suggest that while starvation alone may be enough to slowly quench satellite galaxies, direct gas stripping, particularly at pericenters, is required to produce the short quenching time-scales exhibited in the simulation.
Publisher: Oxford University Press (OUP)
Date: 09-03-2018
DOI: 10.1093/MNRAS/STY242
Publisher: Oxford University Press (OUP)
Date: 13-07-2017
Publisher: Springer Science and Business Media LLC
Date: 26-08-2020
DOI: 10.1186/S13673-020-00243-9
Abstract: Vehicular cooperation mechanisms are known to provide efficiency and scalability benefits but for the mechanisms to be human-centric, there is a need for them to be robust and resilient to anti-social behaviours such as deception. More specifically, decentralised vehicle-to-vehicle cooperation has been shown to be an effective and convenient approach to coordinate the use of dynamically changing common road resources such as car parking. However, the potential for selfish behaviour of some vehicles in the form of sending false information for self-benefit has a significant effect on the value of cooperation. In this paper, we investigate, via extensive simulations, the deception behaviour of malicious vehicles looking to park by sending false information in decentralized vehicle cooperation. Furthermore, Deception Detection Mechanisms (DDMs) are introduced and are shown to be valuable in ameliorating the effects of malicious vehicles. The work has broader implications for an open world of autonomous and adaptive systems with decentralized control and ownership which need to cooperate to use shared resources they are susceptible to malicious behaviour, and hence, need to be built to be robust to such behaviour.
Publisher: Oxford University Press (OUP)
Date: 25-11-2020
Abstract: We examine how the post-processed content of molecular hydrogen (H2) in galaxies from the TNG100 cosmological, hydrodynamic simulation changes with environment at z = 0, assessing central/satellite status and host halo mass. We make close comparisons with the carbon monoxide (CO) emission survey xCOLD GASS where possible, having mock-observed TNG100 galaxies to match the survey’s specifications. For a representative s le of host haloes across 1011 ≲ M200c/M⊙ & 1014.6, TNG100 predicts that satellites with $m_* \\ge 10^9\\, {\\rm M}_{\\odot }$ should have a median deficit in their H2 fractions of ∼0.6 dex relative to centrals of the same stellar mass. Once observational and group-finding uncertainties are accounted for, the signature of this deficit decreases to ∼0.2 dex. Remarkably, we calculate a deficit in xCOLD GASS satellites’ H2 content relative to centrals of 0.2–0.3 dex, in line with our prediction. We further show that TNG100 and SDSS data exhibit continuous declines in the average star formation rates of galaxies at fixed stellar mass in denser environments, in quantitative agreement with each other. By tracking satellites from their moment of infall in TNG100, we directly show that atomic hydrogen (H i) is depleted at fractionally higher rates than H2 on average. Supporting this picture, we find that the H2/H i mass ratios of satellites are elevated relative to centrals in xCOLD GASS. We provide additional predictions for the effect of environment on H2 – both absolute and relative to H i – that can be tested with spectral stacking in future CO surveys.
Publisher: Oxford University Press (OUP)
Date: 23-11-2018
Publisher: Oxford University Press (OUP)
Date: 11-12-2017
Publisher: EDP Sciences
Date: 07-2010
Publisher: Oxford University Press (OUP)
Date: 09-2022
DOI: 10.1093/IA/IIAC177
Publisher: Oxford University Press (OUP)
Date: 18-07-2016
Publisher: Oxford University Press (OUP)
Date: 24-08-2017
Publisher: American Astronomical Society
Date: 13-08-2012
Publisher: Cambridge University Press (CUP)
Date: 07-2014
DOI: 10.1017/S1743921315003488
Abstract: The Sydney–AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey is an ongoing project to obtain spatially resolved spectroscopic observations of ~3400 galaxies by mid-2016. To date, a total of ~1000 galaxies have been observed, making the SAMI Galaxy Survey the largest integral field survey in existence. In July 2014 the early data release for the SAMI galaxy Survey occurred, with over 100 galaxies available to the community. The richness of the SAMI dataset allows a vast array of science. We highlight some of the early science results from the project, including the discovery and analysis of galactic winds, the distribution of fast and slow rotating early type galaxies, and the unification of galaxy scaling relations.
Publisher: EDP Sciences
Date: 08-2012
Publisher: Oxford University Press (OUP)
Date: 25-11-2016
Publisher: American Astronomical Society
Date: 24-04-2017
Publisher: Oxford University Press (OUP)
Date: 21-03-2007
Publisher: Oxford University Press (OUP)
Date: 07-10-2022
Abstract: Misalignments between the rotation axis of stars and gas are an indication of external processes shaping galaxies throughout their evolution. Using observations of 3068 galaxies from the SAMI Galaxy Survey, we compute global kinematic position angles for 1445 objects with reliable kinematics and identify 169 (12 per cent) galaxies which show stellar-gas misalignments. Kinematically decoupled features are more prevalent in early-type assive galaxies compared to late-type/star-forming systems. Star formation is the main source of gas ionization in only 22 per cent of misaligned galaxies 17 per cent are Seyfert objects, while 61 per cent show Low-Ionization Nuclear Emission-line Region features. We identify the most probable physical cause of the kinematic decoupling and find that, while accretion-driven cases are dominant, for up to 8 per cent of our s le, the misalignment may be tracing outflowing gas. When considering only misalignments driven by accretion, the acquired gas is feeding active star formation in only ∼1/4 of cases. As a population, misaligned galaxies have higher Sérsic indices and lower stellar spin and specific star formation rates than appropriately matched s les of aligned systems. These results suggest that both morphology and star formation/gas content are significantly correlated with the prevalence and timescales of misalignments. Specifically, torques on misaligned gas discs are smaller for more centrally concentrated galaxies, while the newly accreted gas feels lower viscous drag forces in more gas-poor objects. Marginal evidence of star formation not being correlated with misalignment likelihood for late-type galaxies suggests that such morphologies in the nearby Universe might be the result of preferentially aligned accretion at higher redshifts.
Publisher: Oxford University Press (OUP)
Date: 03-05-2017
DOI: 10.1093/MNRAS/STX958
Publisher: Oxford University Press (OUP)
Date: 16-06-2015
Publisher: Oxford University Press (OUP)
Date: 17-09-2007
Publisher: Elsevier BV
Date: 08-1986
DOI: 10.1016/S0015-0282(16)49521-X
Abstract: The implantation rates and subsequent pregnancy rates in in vitro fertilization (IVF) programs are lower than those currently seen in the normal fertile population. During IVF treatment regimens, intercourse is not allowed and artificial insemination is normally excluded. This trial, involving the deposition of semen in the high vaginal area, was undertaken for evaluation of the influence of sperm in the reproductive tract on subsequent implantation rates. The results show that the implantation rate, as assessed by a rise in the human chorionic gonadotropin levels in inseminated patients, was 53%, compared with 23% in the control group. The implantation rate of 54% in the group who had tubal occlusion or no fallopian tubes was not significantly different from the implantation rate of 50% in the group with patent tubes, which suggests that the site of sperm influence was on the endometrium and that the absence of the fallopian tube has no significant effect upon this influence.
Publisher: Springer Science and Business Media LLC
Date: 22-09-2022
Publisher: EDP Sciences
Date: 08-2014
Publisher: American Astronomical Society
Date: 08-08-2014
Publisher: Oxford University Press (OUP)
Date: 14-06-2018
Publisher: Oxford University Press (OUP)
Date: 16-01-2018
DOI: 10.1093/MNRAS/STY127
Publisher: Oxford University Press (OUP)
Date: 09-2013
Publisher: Oxford University Press (OUP)
Date: 08-09-2022
Abstract: We use a s le of 559 disc galaxies extracted from the eXtended GALEX Arecibo SDSS Survey to study the connection between baryonic angular momentum, mass, and atomic gas fraction in the local Universe. Baryonic angular momenta are determined by combining H i and H2 integrated profiles with 2D stellar mass surface density profiles. In line with previous work, we confirm that specific angular momentum and atomic gas fraction are tightly correlated, but we find a larger scatter than previously observed. This is most likely due to the wider range of galaxy properties covered by our s le. We compare our findings with the predictions of the analytical stability model developed by Obreschkow et al. and find that, while the model provides a very good first-order approximation for the connection between baryonic angular momentum, mass, and gas fraction, it does not fully match our data. Specifically, we find that at fixed baryonic mass, the dependence of specific angular momentum on gas fraction is significantly weaker, and at fixed gas fraction, the slope of the angular momentum versus mass relation is shallower than what was predicted by the model. The reasons behind this tension remain unclear, but we speculate that multiple factors may simultaneously play a role, all related to the fact that the model is not able to encapsulate the full ersity of galaxy properties in our s le.
Publisher: Oxford University Press (OUP)
Date: 09-01-2019
Publisher: Oxford University Press (OUP)
Date: 27-04-2022
Abstract: The stellar surface density within the inner 1 kpc (Σ1) has become a popular tool for understanding the growth of galaxies and its connection with the quenching of star formation. The emerging picture suggests that building a central dense core is a necessary condition for quenching. However, it is not clear whether changes in Σ1 trace changes in stellar kinematics and the growth of dispersion-dominated bulges. In this paper, we combine imaging from the Sloan Digital Sky Survey with stellar kinematics from the Sydney-AAO Multi-object Integral-field unit and Mapping Nearby Galaxies at Apache Point Observatory surveys to quantify the correlation between Σ1 and the proxy for stellar spin parameter within one effective radius (λre) for 1599 nearby galaxies. We show that, on the star-forming main sequence and at fixed stellar mass, changes in Σ1 are mirrored by changes in λre. While forming stars, main-sequence galaxies remain rotationally-dominated systems, with their Σ1 increasing but their stellar spin staying either constant or slightly increasing. The picture changes below the main sequence, where Σ1 and λre are no longer correlated. Passive systems show a narrower range of Σ1, but a wider range of λre compared to star-forming galaxies. Our results indicate that, from a structural point of view, passive galaxies are a more heterogeneous population than star-forming systems, and may have followed a variety of evolutionary paths. This also suggests that, if dispersion-dominated bulges still grow significantly at z ∼ 0, this generally takes place during, or after, the quenching phase.
Publisher: Springer Science and Business Media LLC
Date: 23-04-2018
Publisher: Oxford University Press (OUP)
Date: 07-10-2019
Abstract: We present a structural decomposition analysis of the galaxies in the extended GALEX Arecibo SDSS Survey (xGASS) using (gri) images from the Sloan Digital Sky Survey. Utilizing the 2D Bayesian light profile fitting code ProFit, we fit single- and double-component models taking advantage of a robust Markov chain Monte Carlo optimization algorithm in which we assume a Sérsic profile for single-component models and a combination of a Sérsic bulge and near-exponential disc (0.5 ≤ n ≤ 1.5) for double-component models. We investigate the effect of bulges on the atomic hydrogen (H i) content in galaxies by revisiting the H i-to-stellar mass scaling relations with the bulge-to-total ratio measured in the ProFit decompositions. We show that, at both fixed total and disc stellar mass, more bulge-dominated galaxies have systematically lower H i masses, implying that bulge-dominated galaxies with large H i reservoirs are rare in the local Universe. We see similar trends when separating galaxies by a bulge-to-total ratio based either on luminosity or stellar mass, however, the trends are more evident with luminosity. Importantly, when controlling for both stellar mass and star formation rate, the separation of atomic gas content reduces to within 0.3 dex between galaxies of different bulge-to-total ratios. Our findings suggest that the presence of a photometric bulge has little effect on the global H i gas reservoirs of local galaxies.
Publisher: Oxford University Press (OUP)
Date: 22-05-2020
Abstract: We present the KMOS-CLASH (K-CLASH) survey, a K-band Multi-Object Spectrograph (KMOS) survey, of the spatially resolved gas properties and kinematics of 191 (pre-dominantly blue) H α-detected galaxies at 0.2 ≲ z ≲ 0.6 in field and cluster environments. K-CLASH targets galaxies in four Cluster Lensing And Supernova survey with Hubble (CLASH) fields in the KMOS IZ-band, over 7 arcmin radius (≈2–3 Mpc) fields of view. K-CLASH aims to study the transition of star-forming galaxies from turbulent, highly star-forming disc-like and peculiar systems at z ≈ 1–3, to the comparatively quiescent, ordered late-type galaxies at z ≈ 0, and to examine the role of clusters in the build-up of the red sequence since z ≈ 1. In this paper, we describe the K-CLASH survey, present the s le, and provide an overview of the K-CLASH galaxy properties. We demonstrate that our s le comprises star-forming galaxies typical of their stellar masses and epochs, residing both in field and cluster environments. We conclude K-CLASH provides an ideal s le to bridge the gap between existing large integral-field spectroscopy surveys at higher and lower redshifts. We find that star-forming K-CLASH cluster galaxies at intermediate redshifts have systematically lower stellar masses than their star-forming counterparts in the field, hinting at possible ‘downsizing’ scenarios of galaxy growth in clusters at these epochs. We measure no difference between the star formation rates of H α-detected, star-forming galaxies in either environment after accounting for stellar mass, suggesting that cluster quenching occurs very rapidly during the epochs probed by K-CLASH, or that star-forming K-CLASH galaxies in clusters have only recently arrived there, with insufficient time elapsed for quenching to have occurred.
Publisher: EDP Sciences
Date: 02-2015
Publisher: EDP Sciences
Date: 07-2014
Publisher: Oxford University Press (OUP)
Date: 03-2021
Abstract: Galaxy internal structure growth has long been accused of inhibiting star formation in disc galaxies. We investigate the potential physical connection between the growth of dispersion-supported stellar structures (e.g. classical bulges) and the position of galaxies on the star-forming main sequence at z ∼ 0. Combining the might of the SAMI and MaNGA galaxy surveys, we measure the λRe spin parameter for 3289 galaxies over $9.5 \\lt \\log M_{\\star } [\\rm {M}_{\\odot }] \\lt 12$. At all stellar masses, galaxies at the locus of the main sequence possess λRe values indicative of intrinsically flattened discs. However, above $\\log M_{\\star }[\\rm {M}_{\\odot }]\\sim 10.5$ where the main sequence starts bending, we find tantalizing evidence for an increase in the number of galaxies with dispersion-supported structures, perhaps suggesting a connection between bulges and the bending of the main sequence. Moving above the main sequence, we see no evidence of any change in the typical spin parameter in galaxies once gravitationally interacting systems are excluded from the s le. Similarly, up to 1 dex below the main sequence, λRe remains roughly constant and only at very high stellar masses ($\\log M_{\\star }[\\rm {M}_{\\odot }]\\gt 11$), do we see a rapid decrease in λRe once galaxies decline in star formation activity. If this trend is confirmed, it would be indicative of different quenching mechanisms acting on high- and low-mass galaxies. The results suggest that whilst a population of galaxies possessing some dispersion-supported structure is already present on the star-forming main sequence, further growth would be required after the galaxy has quenched to match the kinematic properties observed in passive galaxies at z ∼ 0.
Publisher: EDP Sciences
Date: 11-2014
Publisher: MDPI AG
Date: 19-02-2022
DOI: 10.3390/S22041632
Abstract: Satisfying a context consumer’s quality of context (QoC) requirements is important to context management platforms (CMPs) in order to have credibility. QoC indicates the contextual information’s quality metrics (e.g., accuracy, timeliness, completeness). The outcomes of these metrics depend on the functional and quality characteristics associated with all actors (context consumers (or) context-aware applications, CMPs, and context providers (or) IoT-data providers) in context-aware IoT environments. This survey identifies and studies such characteristics and highlights the limitations in actors’ current functionalities and QoC modelling approaches to obtain adequate QoC and improve context consumers’ quality of experience (QoE). We propose a novel concept system based on our critical analysis this system addresses the functional limitations in existing QoC modelling approaches. Moreover, we highlight those QoC metrics affected by quality of service (QoS) metrics in CMPs. These recommendations provide CMP developers with a reference system they could incorporate, functionalities and QoS metrics to maintain in order to deliver an adequate QoC.
Publisher: Oxford University Press (OUP)
Date: 03-07-2020
Abstract: We present a comparison of galaxy atomic and molecular gas properties in three recent cosmological hydrodynamic simulations, namely SIMBA, EAGLE, and IllustrisTNG, versus observations from z ∼ 0 to 2. These simulations all rely on similar subresolution prescriptions to model cold interstellar gas that they cannot represent directly, and qualitatively reproduce the observed z ≈ 0 H i and H2 mass functions (HIMFs and H2MFs, respectively), CO(1–0) luminosity functions (COLFs), and gas scaling relations versus stellar mass, specific star formation rate, and stellar surface density μ*, with some quantitative differences. To compare to the COLF, we apply an H2-to-CO conversion factor to the simulated galaxies based on their average molecular surface density and metallicity, yielding substantial variations in αCO and significant differences between models. Using this, predicted z = 0 COLFs agree better with data than predicted H2MFs. Out to z ∼ 2, EAGLE’s and SIMBA’s HIMFs and COLFs strongly increase, while IllustrisTNG’s HIMF declines and COLF evolves slowly. EAGLE and simba reproduce high-LCO(1–0) galaxies at z ∼ 1–2 as observed, owing partly to a median αCO(z = 2) ∼ 1 versus αCO(z = 0) ∼ 3. Examining H i, H2, and CO scaling relations, their trends with M* are broadly reproduced in all models, but EAGLE yields too little H i in green valley galaxies, IllustrisTNG and SIMBA overproduce cold gas in massive galaxies, and SIMBA overproduces molecular gas in small systems. Using SIMBA variants that exclude in idual active galactic nucleus (AGN) feedback modules, we find that SIMBA’s AGN jet feedback is primarily responsible by lowering cold gas contents from z ∼ 1 → 0 by suppressing cold gas in $M_*\\gtrsim 10^{10}{\\rm \\,M}_\\odot$ galaxies, while X-ray feedback suppresses the formation of high-μ* systems.
Publisher: Oxford University Press (OUP)
Date: 29-01-2021
Abstract: We measure the gas-phase metallicity gradients of 248 galaxies selected from Data Release 2 of the SAMI Galaxy Survey. We demonstrate that there are large systematic discrepancies between the metallicity gradients derived using common strong emission line metallicity diagnostics. We determine which pairs of diagnostics have Spearman’s rank coefficients greater than 0.6 and provide linear conversions to allow the accurate comparison of metallicity gradients derived using different strong emission line diagnostics. For galaxies within the mass range 8.5 & log (M/M⊙) & 11.0, we find discrepancies of up to 0.11 dex/Re between seven popular diagnostics in the metallicity gradient–mass relation. We find a suggestion of a break in the metallicity gradient–mass relation, where the slope shifts from negative to positive, occurs between 9.5 & log (M/M⊙) & 10.5 for the seven chosen diagnostics. Applying our conversions to the metallicity gradient–mass relation, we reduce the maximum dispersion from 0.11 dex/Re to 0.02 dex/Re. These conversions provide the most accurate method of converting metallicity gradients when key emission lines are unavailable. We find that diagnostics that share common sets of emission line ratios agree best, and that diagnostics calibrated through the electron temperature provide more consistent results compared to those calibrated through photoionization models.
Publisher: American Astronomical Society
Date: 18-03-2005
DOI: 10.1086/429993
Publisher: EDP Sciences
Date: 04-2014
Publisher: EDP Sciences
Date: 10-03-2011
Publisher: EDP Sciences
Date: 04-2014
Publisher: Oxford University Press (OUP)
Date: 24-07-2015
Publisher: EDP Sciences
Date: 30-05-2013
Publisher: Oxford University Press (OUP)
Date: 23-12-2016
Publisher: EDP Sciences
Date: 04-2014
Publisher: Oxford University Press (OUP)
Date: 02-08-2018
Publisher: Oxford University Press (OUP)
Date: 20-11-2015
Publisher: Oxford University Press (OUP)
Date: 29-01-2018
DOI: 10.1093/MNRAS/STY214
Publisher: Oxford University Press (OUP)
Date: 28-08-2021
Abstract: We apply a spectral stacking technique to Westerbork Synthesis Radio Telescope observations to measure the neutral atomic hydrogen content (H i) of nearby galaxies in and around galaxy groups at z & 0.11. Our s le includes 577 optically selected galaxies (120 isolated galaxies and 457 satellites) covering stellar masses between 1010 and 1011.5 M⊙, cross-matched with Yang’s group catalogue, with angular and redshift positions from the Sloan Digital Sky Survey. We find that the satellites in the centres of groups have lower H i masses at fixed stellar mass and morphology (characterized by the inverse concentration index) relative to those at larger radii. These trends persist for satellites in both high-mass ($M_{\\rm halo} \\gt 10^{13.5}\\, h^{-1}\\, \\mathrm{M}_{\\odot }$) and low-mass ($M_{\\rm halo} \\leqslant 10^{13.5}\\, h^{-1}\\, \\mathrm{M}_{\\odot }$) groups, but disappear if we only consider group members in low local density (Σ & 5 gal Mpc−2) environments. Similar trends are found for the specific star formation rate. Interestingly, we find that the radial trends of decreasing H i mass with decreasing group-centric radius extend beyond the group virial radius, as isolated galaxies close to larger groups lack H i compared with those located more than ∼3.0 R180 away from the centre of their nearest group. We also measure these trends in the late-type subs le and obtain similar results. Our results suggest that the H i reservoir of galaxies can be affected before galaxies become group satellites, indicating the existence of pre-processing in the infalling isolated galaxies.
Publisher: Oxford University Press (OUP)
Date: 04-12-2021
Abstract: We present results from our analysis of the Hydra I cluster observed in neutral atomic hydrogen (H i) as part of the Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY). These WALLABY observations cover a 60-square-degree field of view with uniform sensitivity and a spatial resolution of 30 arcsec. We use these wide-field observations to investigate the effect of galaxy environment on H i gas removal and star formation quenching by comparing the properties of cluster, infall, and field galaxies extending up to ∼5R200 from the cluster centre. We find a sharp decrease in the H i-detected fraction of infalling galaxies at a projected distance of ∼1.5R200 from the cluster centre from $\\sim 85{{\\ \\rm per\\ cent}}$ to $\\sim 35{{\\ \\rm per\\ cent}}$. We see evidence for the environment removing gas from the outskirts of H i-detected cluster and infall galaxies through the decrease in the H i to r-band optical disc diameter ratio. These galaxies lie on the star-forming main sequence, indicating that gas removal is not yet affecting the inner star-forming discs and is limited to the galaxy outskirts. Although we do not detect galaxies undergoing galaxy-wide quenching, we do observe a reduction in recent star formation in the outer disc of cluster galaxies, which is likely due to the smaller gas reservoirs present beyond the optical radius in these galaxies. Stacking of H i non-detections with H i masses below $M_{\\rm {HI}}\\lesssim 10^{8.4}\\, \\rm {M}_{\\odot }$ will be required to probe the H i of galaxies undergoing quenching at distances ≳60 Mpc with WALLABY.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-08-2022
DOI: 10.36227/TECHRXIV.20445015.V1
Abstract: This article is under review and upon acceptance: Personal use of this material is permitted. However, permission to use this material for any other purposes must be obtained from the IEEE by sending a request to pubs-permissions@ieee.org. (Copyright (c) 2015 IEEE.)
Publisher: Wiley
Date: 31-05-2013
Publisher: EDP Sciences
Date: 25-08-2008
Publisher: Oxford University Press (OUP)
Date: 07-12-2022
Abstract: We present SAMI-H i, a survey of the atomic hydrogen content of 296 galaxies with integral field spectroscopy available from the SAMI Galaxy Survey. The s le spans nearly 4 dex in stellar mass ($M_\\star = 10^{7.4}-10^{11.1}~ \\rm M_\\odot$), redshift z & 0.06, and includes new Arecibo observations of 153 galaxies, for which we release catalogues and H i spectra. We use these data to compare the rotational velocities obtained from optical and radio observations and to show how systematic differences affect the slope and scatter of the stellar-mass and baryonic Tully–Fisher relations. Specifically, we show that $\\rm H\\alpha$ rotational velocities measured in the inner parts of galaxies (1.3 effective radii in this work) systematically underestimate H i global measurements, with H i/$\\rm H\\alpha$ velocity ratios that increase at low stellar masses, where rotation curves are typically still rising and $\\rm H\\alpha$ measurements do not reach their plateau. As a result, the $\\rm H\\alpha$ stellar mass Tully–Fisher relation is steeper (when M⋆ is the independent variable) and has larger scatter than its H i counterpart. Interestingly, we confirm the presence of a small fraction of low-mass outliers of the $\\rm H\\alpha$ relation that are not present when H i velocity widths are used and are not explained by ‘aperture effects’. These appear to be highly disturbed systems for which $\\rm H\\alpha$ widths do not provide a reliable estimate of the rotational velocity. Our analysis reaffirms the importance of taking into account differences in velocity definitions as well as tracers used when interpreting offsets from the Tully–Fisher relation, at both low and high redshifts and when comparing with simulations.
Publisher: EDP Sciences
Date: 07-2010
Publisher: SAGE Publications
Date: 10-07-2018
Abstract: Background. Proportional motor recovery in the upper limb has been investigated, indicating about 70% of the potential for recovery of motor impairment within the first months poststroke. Objective. To investigate whether the proportional recovery rule is applicable for upper-limb somatosensory impairment and to study underlying neural correlates of impairment and outcome at 6 months. Methods. A total of 32 patients were evaluated at 4 to 7 days and 6 months using the Erasmus MC modification of the revised Nottingham Sensory Assessment (NSA) for impairment of (1) somatosensory perception (exteroception) and (2) passive somatosensory processing (sharp/blunt discrimination and proprioception) (3) active somatosensory processing was evaluated using the stereognosis component of the NSA. Magnetic resonance imaging scans were obtained within 1 week poststroke, from which lesion load (LL) was calculated for key somatosensory tracts. Results. Somatosensory perception fully recovered within 6 months. Passive and active somatosensory processing showed proportional recovery of 86% (95% CI = 79%-93%) and 69% (95% CI = 49%-89%), respectively. Patients with somatosensory impairment at 4 to 7 days showed significantly greater thalamocortical and insulo-opercular tracts (TCT and IOT) LL ( P .05) in comparison to patients without impairment. Sensorimotor tract disruption at 4 to 7 days did not provide significant contribution above somatosensory processing score at 4 to 7 days when predicting somatosensory processing outcome at 6 months. Conclusions. Our s le of stroke patients assessed early showed full somatosensory perception but proportional passive and active somatosensory processing recovery. Disruption of both the TCT and IOT early after stroke appears to be a factor associated with somatosensory impairment but not outcome.
Publisher: American Astronomical Society
Date: 12-2022
Abstract: We measure the molecular-to-atomic gas ratio, R mol , and the star formation rate (SFR) per unit molecular gas mass, SFE mol , in 38 nearby galaxies selected from the Virgo Environment Traced in CO (VERTICO) survey. We stack ALMA 12 CO ( J = 2−1) spectra coherently using H i velocities from the VIVA survey to detect faint CO emission out to galactocentric radii r gal ∼ 1.2 r 25 . We determine the scale lengths for the molecular and stellar components, finding a ∼3:5 relation compared to ∼1:1 in field galaxies, indicating that the CO emission is more centrally concentrated than the stars. We compute R mol as a function of different physical quantities. While the spatially resolved R mol on average decreases with increasing radius, we find that the mean molecular-to-atomic gas ratio within the stellar effective radius R e , R mol ( r R e ), shows a systematic increase with the level of H i , truncation and/or asymmetry (H I perturbation). Analysis of the molecular- and the atomic-to-stellar mass ratios within R e , R ⋆ mol ( r R e ) and R ⋆ atom ( r R e ) , shows that VERTICO galaxies have increasingly lower R ⋆ atom ( r R e ) for larger levels of H I perturbation (compared to field galaxies matched in stellar mass), but no significant change in R ⋆ m o l ( r R e ) . We also measure a clear systematic decrease of the SFE mol within R e , SFE mol ( r R e ), with increasingly perturbed H i . Therefore, compared to field galaxies from the field, VERTICO galaxies are more compact in CO emission in relation to their stellar distribution, but increasingly perturbed atomic gas increases their R mol and decreases the efficiency with which their molecular gas forms stars.
Publisher: Oxford University Press (OUP)
Date: 14-06-2021
Abstract: We present the KMOS Galaxy Evolution Survey (KGES), a K-band Multi-Object Spectrograph (KMOS) study of the H α and [N ii] emission from 288 K-band-selected galaxies at 1.2 ≲ z ≲ 1.8, with stellar masses in the range $\\log _{10}(M_{*}/\\rm {M}_{\\odot })\\approx 9$ – 11.5. In this paper, we describe the survey design, present the s le, and discuss the key properties of the KGES galaxies. We combine KGES with appropriately matched s les at lower redshifts from the KMOS Redshift One Spectroscopic Survey (KROSS) and the SAMI Galaxy Survey. Accounting for the effects of s le selection, data quality, and analysis techniques between surveys, we examine the kinematic characteristics and angular momentum content of star-forming galaxies at z ≈ 1.5, ≈1, and ≈0. We find that stellar mass, rather than redshift, most strongly correlates with the disc fraction amongst star-forming galaxies at z ≲ 1.5, observing only a modest increase in the prevalence of discs between z ≈ 1.5 and z ≈ 0.04 at fixed stellar mass. Furthermore, typical star-forming galaxies follow the same median relation between specific angular momentum and stellar mass, regardless of their redshift, with the normalization of the relation depending more strongly on how disc-like a galaxy’s kinematics are. This suggests that massive star-forming discs form in a very similar manner across the ≈10 Gyr encompassed by our study and that the inferred link between the angular momentum of galaxies and their haloes does not change significantly across the stellar mass and redshift ranges probed in this work.
Publisher: EDP Sciences
Date: 07-2010
Publisher: JMIR Publications Inc.
Date: 06-02-2023
DOI: 10.2196/42566
Abstract: Physician burnout is a common problem, with onset frequently occurring during undergraduate education. Early intervention strategies that train medical students in psychological flexibility skills could support well-being and mitigate burnout risks associated with unmodifiable career stressors. There is a need for randomized controlled trials to assess effectiveness. As psychological flexibility varies contextually and among in iduals, tailoring interventions may improve outcomes. Smartphone apps can facilitate in idualization and accessibility, and the evaluation of this approach is an identified research priority. This study aimed to evaluate the effectiveness of a stand-alone app–delivered Acceptance and Commitment Training intervention for improving medical students’ self-reported burnout, well-being, psychological flexibility, and psychological distress outcomes. We aimed to explore whether an in idualized app would demonstrate benefits over a nonin idualized version. This parallel randomized controlled trial was conducted with a s le of medical students from 2 Australian universities (N=143). Participants were randomly allocated to 1 of 3 intervention arms (in idualized, nonin idualized, and waitlist) using a 1:1:1 allocation ratio. In idualized and nonin idualized participants were blinded to group allocation. The 5-week intervention included an introductory module (stage 1) and on-demand access to short skill training activities (stage 2), which students accessed at their own pace. Stage 2 was either nonin idualized or in idualized to meet students’ identified psychological flexibility training needs. The mean differences in change from baseline between the intervention groups and the waitlist group were not statistically significant for burnout outcomes: exhaustion (primary in idualized: −0.52, 95% CI −3.70 to 2.65, P=.75 nonin idualized: 1.60, 95% CI −1.84 to 5.03, P=.37), cynicism (in idualized: −1.26, 95% CI −4.46 to 1.94, P=.44 nonin idualized: 1.00, 95% CI −2.45 to 4.46, P=.57), and academic efficacy (in idualized: 0.94, 95% CI −0.90 to 2.79, P=.32 nonin idualized: 2.02, 95% CI 0.02-4.03, P=.05). Following the intervention, the in idualized group demonstrated improved psychological flexibility (0.50, 95% CI 0.12-0.89 P=.01), reduced inflexibility (0.48, 95% CI −0.92 to −0.04 P=.04), and reduced stress (−6.89, 95% CI −12.01 to 5.99 P=.01), and the nonin idualized group demonstrated improved well-being (6.46, 95% CI 0.49-12.42 P=.04) and stress (−6.36, 95% CI −11.90 to −0.83 P=.03) compared with waitlist participants. Between-group differences for the in idualized and nonin idualized arms were not statistically significant. High attrition (75/143, 52.4%) was observed. This trial provides early support for the potential benefits of Acceptance and Commitment Training for medical student well-being and psychological outcomes and demonstrates that psychological flexibility and inflexibility can be trained using a smartphone app. Although postintervention burnout outcomes were not statistically significant, improvements in secondary outcomes could indicate early risk mitigation. Replication studies with larger s les and longer-term follow-up are required, and future research should focus on improving implementation frameworks to increase engagement and optimize in idualization methods. Australian New Zealand Clinical Trials Registry 12621000911897 p92cwrw RR2-10.2196/32992
Publisher: American Astronomical Society
Date: 08-12-2017
Publisher: Oxford University Press (OUP)
Date: 22-11-2012
DOI: 10.1093/MNRAS/STS125
Publisher: Oxford University Press (OUP)
Date: 19-07-2017
Publisher: Oxford University Press (OUP)
Date: 24-05-2019
Abstract: We use data from the Sydney-AAO Multi-object Integral-field spectroscopy (SAMI) Galaxy Survey to study the dynamical scaling relation between galaxy stellar mass M∗ and the general kinematic parameter $S_K = \\sqrt{K V_{\\rm rot}^2 + \\sigma ^2}$ that combines rotation velocity Vrot and velocity dispersion σ. We show that the log M∗ – log SK relation: (1) is linear above limits set by properties of the s les and observations (2) has slightly different slope when derived from stellar or gas kinematic measurements (3) applies to both early-type and late-type galaxies and has smaller scatter than either the Tully–Fisher relation (log M∗ − log Vrot) for late types or the Faber–Jackson relation (log M∗ − log σ) for early types and (4) has scatter that is only weakly sensitive to the value of K, with minimum scatter for K in the range 0.4 and 0.7. We compare SK to the aperture second moment (the ‘aperture velocity dispersion’) measured from the integrated spectrum within a 3-arcsecond radius aperture ($\\sigma _{3^{\\prime \\prime }}$). We find that while SK and $\\sigma _{3^{\\prime \\prime }}$ are in general tightly correlated, the log M∗ − log SK relation has less scatter than the $\\log M_* - \\log \\sigma _{3^{\\prime \\prime }}$ relation.
Publisher: EDP Sciences
Date: 07-2010
Publisher: EDP Sciences
Date: 04-2021
DOI: 10.1051/0004-6361/202039803
Abstract: We present the first interferometric blind H I survey of the Fornax galaxy cluster, which covers an area of 15 deg 2 out to the cluster virial radius. The survey has a spatial and velocity resolution of 67″ × 95″(∼6 × 9 kpc at the Fornax cluster distance of 20 Mpc) and 6.6 km s −1 and a 3 σ sensitivity of N H I ∼ 2 × 10 19 cm −2 and M H I ∼ 2 × 10 7 M ⊙ , respectively. We detect 16 galaxies out of roughly 200 spectroscopically confirmed Fornax cluster members. The detections cover about three orders of magnitude in H I mass, from 8 × 10 6 to 1.5 × 10 10 M ⊙ . They avoid the central, virialised region of the cluster both on the sky and in projected phase-space, showing that they are recent arrivals and that, in Fornax, H I is lost within a crossing time, ∼2 Gyr. Half of these galaxies exhibit a disturbed H I morphology, including several cases of asymmetries, tails, offsets between H I and optical centres, and a case of a truncated H I disc. This suggests that these recent arrivals have been interacting with other galaxies, the large-scale potential or the intergalactic medium, within or on their way to Fornax. As a whole, our Fornax H I detections are H I -poorer and form stars at a lower rate than non-cluster galaxies in the same M ⋆ range. This is particularly evident at M ⋆ ≲ 10 9 M ⊙ , indicating that low mass galaxies are more strongly affected throughout their infall towards the cluster. The M H I / M ⋆ ratio of Fornax galaxies is comparable to that in the Virgo cluster . At fixed M ⋆ , our H I detections follow the non-cluster relation between M H I and the star formation rate, and we argue that this implies that thus far they have lost their H I on a timescale ≳1−2 Gyr. Deeper inside the cluster H I removal is likely to proceed faster, as confirmed by a population of H I -undetected but H 2 -detected star-forming galaxies. Overall, based on ALMA data, we find a large scatter in H 2 -to-H I mass ratio, with several galaxies showing an unusually high ratio that is probably caused by faster H I removal. Finally, we identify an H I -rich subgroup of possible interacting galaxies dominated by NGC 1365, where pre-processing is likely to have taken place.
Publisher: EDP Sciences
Date: 07-2010
Publisher: EDP Sciences
Date: 07-2010
Publisher: EDP Sciences
Date: 07-2010
Publisher: Oxford University Press (OUP)
Date: 04-11-2010
Publisher: Oxford University Press (OUP)
Date: 04-06-2020
Abstract: We use Milky Way-like chemodynamical simulations with a new treatment for dust destruction and growth to investigate how these two processes affect the properties of the interstellar medium in galaxies. We focus on the role of two specific parameters, namely fdes (a new parameter that determines the fraction of dust destroyed in a single gas particle vicinity of a supernova) and Cs (the probability that a metal atom or ion sticks to the dust grain after colliding, i.e. the sticking coefficient), in regulating the amount and distribution of dust, cold gas and metals in galaxies. We find that simulated galaxies with low fdes and/or high Cs values not only produce more dust, but they also have a shallower correlation between the dust surface density and the total gas surface density, and a steeper correlation between the dust-to-gas ratio and the metallicity. Only for values of fdes between 0.01 and 0.02, and of Cs between 0.5 and 1 do our simulations produce an average slope of the dust-to-gas ratio versus metallicity relationship that is consistent with observations. fdes values correspond to a total fraction of dust destroyed by a single supernova ranging between 0.42 and 0.44. Finally, we compare predictions of several simulations (with different star formation recipes, gas fractions, central metallicities, and metallicity gradients) with the spatially resolved M101 galaxy, and conclude that metallicity is the primary driver of the spatial distribution of dust, while the dust-to-gas ratio controls the cold gas distribution, as it regulates the atomc-to-molecular hydrogen conversion rate.
Publisher: American Astronomical Society
Date: 13-11-2009
Publisher: Journal of Orthopaedic & Sports Physical Therapy (JOSPT)
Date: 09-2022
Abstract: To assess the effectiveness of patient education with "myths and facts" versus "facts only" on recall of back pain information and fear-avoidance beliefs in patients with chronic low back pain (LBP). Randomized Study Within A Trial. One hundred fifty-two participants with chronic LBP were included. Participants allocated to the "facts only" group received an information sheet with 6 LBP facts, whereas those allocated to the "myths and facts" group received the same information sheet, with each myth refuted by its respective fact. The primary outcome was a correct recall of back pain facts, and the secondary outcome was the physical activity component of the Fear-Avoidance Beliefs Questionnaire (FABQ-PA), 2 weeks after the provision of the information sheet. There was no evidence of a difference in the proportion of participants with a correct recall between the "myths and facts" and "facts only" groups (odds ratio = 0.98 95% confidence interval [CI]: 0.48, 1.99) and no significant difference in FABQ-PA mean scores between groups (-1.58 95% CI: -3.77, 0.61). Sensitivity analyses adjusted for prognostic factors showed no difference in information recall but a larger difference in FABQ-PA scores (-2.3 95% CI: -4.56, -0.04). We found no overall difference in the recall of back pain information for patients provided with "myths and facts" compared with that for patients provided with "facts only" and a slight reduction in fear-avoidance beliefs for physical activity using "myths and facts" compared with that using "facts only," but the meaningfulness of this result is uncertain.
Publisher: Oxford University Press (OUP)
Date: 03-02-2020
Abstract: We use spectral stacking to measure the contribution of galaxies of different masses and in different hierarchies to the cosmic atomic hydrogen (H i) mass density in the local Universe. Our s le includes 1793 galaxies at z & 0.11 observed with the Westerbork Synthesis Radio Telescope, for which Sloan Digital Sky Survey spectroscopy and hierarchy information are also available. We find a cosmic H i mass density of $\\Omega _{\\rm H\\, \\small {I} } = (3.99 \\pm 0.54)\\times 10^{-4} \\, h_{70}^{-1}$ at 〈 z〉 = 0.065. For the central and satellite galaxies, we obtain $\\Omega _{\\rm H\\, {\\small {I}}}$ of $(3.51 \\pm 0.49)\\times 10^{-4} \\, h_{70}^{-1}$ and $(0.90 \\pm 0.16)\\times 10^{-4} \\, h_{70}^{-1}$, respectively. We show that galaxies above and below stellar masses of ∼109.3 M⊙ contribute in roughly equal measure to the global value of $\\Omega _{\\rm H\\, \\small {I} }$. While consistent with estimates based on targeted H i surveys, our results are in tension with previous theoretical work. We show that these differences are, at least partly, due to the empirical recipe used to set the partition between atomic and molecular hydrogen in semi-analytical models. Moreover, comparing our measurements with the cosmological semi-analytic models of galaxy formation Shark and GALFORM reveals gradual stripping of gas via ram pressure works better to fully reproduce the properties of satellite galaxies in our s le than strangulation. Our findings highlight the power of this approach in constraining theoretical models and confirm the non-negligible contribution of massive galaxies to the H i mass budget of the local Universe.
Publisher: Oxford University Press (OUP)
Date: 03-11-2018
Publisher: Oxford University Press (OUP)
Date: 21-03-2010
Publisher: Oxford University Press (OUP)
Date: 18-11-2011
Publisher: Oxford University Press (OUP)
Date: 23-01-2012
Publisher: Oxford University Press (OUP)
Date: 02-2021
Abstract: We have entered a new era where integral-field spectroscopic surveys of galaxies are sufficiently large to adequately s le large-scale structure over a cosmologically significant volume. This was the primary design goal of the SAMI Galaxy Survey. Here, in Data Release 3, we release data for the full s le of 3068 unique galaxies observed. This includes the SAMI cluster s le of 888 unique galaxies for the first time. For each galaxy, there are two primary spectral cubes covering the blue (370–570 nm) and red (630–740 nm) optical wavelength ranges at spectral resolving power of R = 1808 and 4304, respectively. For each primary cube, we also provide three spatially binned spectral cubes and a set of standardized aperture spectra. For each galaxy, we include complete 2D maps from parametrized fitting to the emission-line and absorption-line spectral data. These maps provide information on the gas ionization and kinematics, stellar kinematics and populations, and more. All data are available online through Australian Astronomical Optics Data Central.
Publisher: American Astronomical Society
Date: 10-11-2021
Publisher: American Astronomical Society
Date: 15-03-2012
Publisher: Oxford University Press (OUP)
Date: 18-11-2018
Publisher: Oxford University Press (OUP)
Date: 21-11-2019
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 11-2022
DOI: 10.1161/STROKEAHA.122.038956
Abstract: Achieving safe, independent, and efficient walking is a top priority for stroke survivors to enable quality of life and future health. This narrative review explores the state of the science in walking recovery after stroke and potential for development. The importance of targeting walking capacity and performance is explored in relation to in idual stroke survivor gait recovery, applying a common language, measurement, classification, prediction, current and future intervention development, and health care delivery. Findings are summarized in a model of current and future stroke walking recovery research and a mission statement is set for researchers and clinicians to drive the field forward to improve the lives of stroke survivors and their carers.
Publisher: Oxford University Press (OUP)
Date: 02-2016
DOI: 10.1093/MNRAS/STW017
Publisher: Oxford University Press (OUP)
Date: 19-12-2023
Abstract: ESO 137-G006 is the brightest cluster galaxy (BCG) of the cool-core and dynamically young Norma cluster. We discover an atomic hydrogen (H i) absorption line associated with this BCG using the Australia Telescope Compact Array. We estimate a gas column density of $\\approx (1.3 \\pm 0.2) \\times 10^{20}\\, T_{\\rm {spin}}$ atoms cm−2 with spin temperature, Tspin ≤ 194 K, consistent with the H i properties of other early-type galaxies and cool-core cluster BCGs. The relationship between the presence of cold gas and a cluster cooling flow is unclear. Our results support the scenario that ESO 137-G006 may be a recent arrival to the cluster centre and not the original BCG. This scenario is consistent with the observed spatial alignment of the BCG’s wide-angle tail radio lobes with Norma’s X-ray sub-cluster and the significant line-of-sight velocity offset between the mean velocity of Norma and that of the BCG.
Publisher: EDP Sciences
Date: 21-09-2004
Publisher: MDPI AG
Date: 11-08-2022
Abstract: Oxidative stress is a key physiological phenomenon underpinning the ageing process and plays a major developmental role in age-associated chronic diseases. This study investigated the antioxidant effects of a polyphenol-rich dietary supplement containing Pinus massoniana bark extract (PMBE) in healthy older adults. In a double-blinded, placebo-controlled clinical trial, participants were randomised (in a 1:1 ratio) to receive a 50 mL/day dietary supplement containing placebo (0 mg PMBE) or PMBE (1322 mg PMBE) for 12 weeks. The primary outcome was fasting plasma malondialdehyde (MDA) concentrations and secondary outcomes were plasma inflammatory markers. MDA concentrations significantly reduced following PMBE for 6 weeks (−1.19 nmol/mL, 95%CI −1.62, −0.75, p 0.001) and 12 weeks (−1.35 nmol/mL, 95%CI −1.74, −0.96, p 0.001) compared to baseline. MDA did not significantly change after the placebo. MDA levels at 6 and 12 weeks were significantly lower following PMBE compared to placebo (p 0.001). At 12 weeks in the PMBE group, fibrinogen concentrations significantly reduced (−0.25 g/L, 95%CI −0.39, −0.11 p 0.0001) and interleukin-6 significantly increased compared to placebo (0.30 pg/mL, 95%CI 0.02, 0.59 p 0.05). PMBE in a polyphenol-rich dietary supplement reduced oxidative stress in healthy older adults. Further studies are warranted to investigate the antioxidant capacity of PMBE in conditions with heightened oxidative stress, such as osteoarthritis, hypertension, type 2 diabetes, or other lifestyle related diseases.
Publisher: Oxford University Press (OUP)
Date: 20-11-2015
Publisher: Oxford University Press (OUP)
Date: 02-07-2020
Abstract: It has been proposed that S0 galaxies are either fading spirals or the result of galaxy mergers. The relative contribution of each pathway and the environments in which they occur remain unknown. Here, we investigate stellar and gas kinematics of 219 S0s in the SAMI Survey to look for signs of multiple formation pathways occurring across the full range of environments. We identify a large range of rotational support in their stellar kinematics, which correspond to ranges in their physical structure. We find that pressure-supported S0s with v/σ below 0.5 tend to be more compact and feature misaligned stellar and gas components, suggesting an external origin for their gas. We postulate that these S0s are consistent with being formed through a merger process. Meanwhile, comparisons of ellipticity, stellar mass, and Sérsic index distributions with spiral galaxies show that the rotationally supported S0s with v/σ above 0.5 are more consistent with a faded spiral origin. In addition, a simulated merger pathway involving a compact elliptical and gas-rich satellite results in an S0 that lies within the pressure-supported group. We conclude that two S0 formation pathways are active, with mergers dominating in isolated galaxies and small groups, and the faded spiral pathway being most prominent in large groups ($10^{13}\\lt \\rm {M_{halo}}\\lt 10^{14}$).
Publisher: EDP Sciences
Date: 12-2018
DOI: 10.1051/0004-6361/201833914
Abstract: We observed the late-type peculiar galaxy NGC 4424 during the Virgo Environmental Survey Tracing Galaxy Evolution (VESTIGE), a blind narrow-band H α +[NII] imaging survey of the Virgo cluster carried out with MegaCam at the Canada-French-Hawaii Telescope (CFHT). The presence of a ∼110 kpc (in projected distance) HI tail in the southern direction indicates that this galaxy is undergoing a ram pressure stripping event. The deep narrow-band image revealed a low surface brightness (Σ(H α ) ≃ 4 × 10 −18 erg s −1 cm −2 arcsec −2 ) ionised gas tail ∼10 kpc in length extending from the centre of the galaxy to the north-west, thus in the direction opposite to the HI tail. Chandra and XMM X-rays data do not show a compact source in the nucleus or an extended tail of hot gas, while IFU spectroscopy (MUSE) indicates that the gas is photo-ionised in the inner regions and shock-ionised in the outer parts. Medium-resolution (MUSE) and high-resolution (Fabry-Perot) IFU spectroscopy confirms that the ionised gas is kinematically decoupled from the stellar component and indicates the presence of two kinematically distinct structures in the stellar disc. The analysis of the SED of the galaxy indicates that the activity of star formation was totally quenched in the outer disc ∼250–280 Myr ago, while only reduced by ∼80% in the central regions. All this observational evidence suggests that NGC 4424 is the remnant of an unequal-mass merger that occurred ≲500 Myr ago when the galaxy was already a member of the Virgo cluster, and is now undergoing a ram pressure stripping event that has removed the gas and quenched the activity of star formation in the outer disc. The tail of ionised gas probably results from the outflow produced by a central starburst fed by the collapse of gas induced by the merging episode. This outflow is sufficiently powerful to overcome the ram pressure induced by the intracluster medium on the disc of the galaxy crossing the cluster. This analysis thus suggests that feedback can participate in the quenching process of galaxies in high-density regions.
Publisher: Oxford University Press (OUP)
Date: 31-10-2019
Abstract: We use the complete Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey to determine the contribution of slow rotators, as well as different types of fast rotators, to the stellar mass function of galaxies in the local Universe. We use stellar kinematics not only to discriminate between fast and slow rotators, but also to distinguish between dynamically cold systems (i.e., consistent with intrinsic axis ratios .3) and systems including a prominent dispersion-supported bulge. We show that fast rotators account for more than $80\\%$ of the stellar mass budget of nearby galaxies, confirming that their number density overwhelms that of slow rotators at almost all masses from 109 to 1011.5M⊙. Most importantly, dynamically cold disks contribute to at least $25\\%$ of the stellar mass budget of the local Universe, significantly higher than what is estimated from visual morphology alone. For stellar masses up to 1010.5M⊙, this class makes up $ =30\\%$ of the galaxy population in each stellar mass bin. The fact that many galaxies that are visually classified as having two-components have stellar spin consistent with dynamically cold disks suggests that the inner component is either rotationally-dominated (e.g., bar, pseudo-bulge) or has little effect on the global stellar kinematics of galaxies.
Publisher: EDP Sciences
Date: 07-2010
Publisher: EDP Sciences
Date: 05-2021
DOI: 10.1051/0004-6361/202038961
Abstract: Context. The xGASS and xCOLD GASS surveys have measured the atomic (H I ) and molecular gas (H 2 ) content of a large and representative s le of nearby galaxies (redshift range of 0.01 z 0.05). Methods. We present optical longslit spectra for a subset of the xGASS and xCOLD GASS galaxies to investigate the correlation between radial metallicity profiles and cold gas content. In addition to previous data, this paper presents new optical spectra for 27 galaxies in the stellar mass range of 9.0 ≤ log M ⋆ [ M ⊙ ] ≤10.0. Methods. The longslit spectra were taken along the major axis of the galaxies, allowing us to obtain radial profiles of the gas-phase oxygen abundance (12 + log(O/H)). The slope of a linear fit to these radial profiles is defined as the metallicity gradient. We investigated correlations between these gradients and global galaxy properties, such as star formation activity and gas content. In addition, we examined the correlation of local metallicity measurements and the global H I mass fraction. Results. We obtained two main results: (i) the local metallicity is correlated with the global H I mass fraction, which is in good agreement with previous results. A simple toy model suggests that this correlation points towards a ‘local gas regulator model’ (ii) the primary driver of metallicity gradients appears to be stellar mass surface density (as a proxy for morphology). Conclusions. This work comprises one of the few systematic observational studies of the influence of the cold gas on the chemical evolution of star-forming galaxies, as considered via metallicity gradients and local measurements of the gas-phase oxygen abundance. Our results suggest that local density and local H I mass fraction are drivers of chemical evolution and the gas-phase metallicity.
Publisher: MDPI AG
Date: 15-05-2023
DOI: 10.3390/S23104767
Abstract: Making internet-of-things (IoT)-based applications context-aware demands large amounts of raw data to be collected, interpreted, stored, and reused or repurposed if needed from many domains and applications. Context is transient but interpreted data can be distinguished from IoT data in many aspects. Managing context in cache is a novel area of research that has been given very little attention. Performance metric-driven adaptive context caching (ACOCA) can have a profound impact on the performance and cost efficiency of context-management platforms (CMPs) when responding to context queries in realtime. Our paper proposes an ACOCA mechanism to maximize both the cost and performance efficiency of a CMP in near realtime. Our novel mechanism encompasses the entire context-management life cycle. This, in turn, distinctively addresses the problems of efficiently selecting context for caching and managing the additional costs of context management in the cache. We demonstrate that our mechanism results in long-term efficiencies for the CMP that have not been observed in any previous study. The mechanism employs a novel, scalable, and selective context-caching agent implemented using the twin delayed deep deterministic policy gradient method. It further incorporates an adaptive context-refresh switching policy, a time-aware eviction policy, and a latent caching decision management policy. We point out in our findings that the additional complexity of adaptation introduced to the CMP through ACOCA is significantly justified, considering the cost and performance gains achieved. Our algorithm is evaluated using a real-world inspired heterogeneous context-query load and a data set based on parking-related traffic in Melbourne, Australia. This paper presents and benchmarks the proposed scheme against traditional and context-aware caching policies. We demonstrate that ACOCA outperforms the benchmarks in both cost and performance efficiency, i.e., up to 68.6%, 84.7%, and 67% more cost efficient compared to traditional data caching policies to cache context, redirector mode, and context-aware adaptive data caching under real-world-like circumstances.
Publisher: Oxford University Press (OUP)
Date: 22-11-2018
Publisher: EDP Sciences
Date: 03-2002
Publisher: EDP Sciences
Date: 07-2010
Publisher: MDPI AG
Date: 06-02-2023
DOI: 10.3390/S23041826
Abstract: With the proliferation of IoT applications, more and more smart, connected devices will be required to communicate with one another, operating in situations that involve erse levels of range and cost requirements, user interactions, mobility, and energy constraints. Wireless technologies that can satisfy the aforementioned requirements will be vital to realise emerging market opportunities in the IoT sector. Bluetooth Mesh is a new wireless protocol that extends the core Bluetooth low energy (BLE) stack and promises to support reliable and scalable IoT systems where thousands of devices such as sensors, smartphones, wearables, robots, and everyday appliances operate together. In this article, we present a comprehensive discussion on current research directions and existing use cases for Bluetooth Mesh, with recommendations for best practices so that researchers and practitioners can better understand how they can use Bluetooth Mesh in IoT scenarios.
Publisher: Oxford University Press (OUP)
Date: 04-01-2008
Publisher: Oxford University Press (OUP)
Date: 30-11-2023
Publisher: American Astronomical Society
Date: 10-2023
Publisher: Oxford University Press (OUP)
Date: 31-10-2017
Publisher: Oxford University Press (OUP)
Date: 06-2019
Abstract: We present an H i study of the galaxy group LGG 351 using Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY) early science data observed with the Australian Square Kilometre Array Pathfinder (ASKAP). LGG 351 resides behind the M 83 group at a velocity range (cz) of ∼3500–4800 km s−1 within the rich Hydra-Centaurus overdensity region. We detect 40 sources with the discovery of a tidally interacting galaxy pair and two new H i sources that are not presented in previous optical catalogues. 23 out of 40 sources have new redshifts derived from the new H i data. This study is the largest WALLABY sub-s le to date and also allows us to further validate the performance of ASKAP and the data reduction pipeline askapsoft. Extended H i emission is seen in six galaxies indicating interaction within the group, although no H i debris is found. We also detect H i in a known ultra-faint dwarf galaxy (dw 1328−29), which demonstrates that it is not a satellite of the M 83 group as previously thought. In conjunction with multiwavelength data, we find that our galaxies follow the atomic gas fraction and baryonic Tully–Fisher scaling relations derived from the GALEX Arecibo SDSS Survey. In addition, majority of our galaxies fall within the star formation main sequence indicating inefficiency of gas removal processes in this loose galaxy group.
Publisher: American Astronomical Society
Date: 20-02-2008
DOI: 10.1086/525513
Publisher: American Astronomical Society
Date: 20-01-2017
Publisher: Oxford University Press (OUP)
Date: 08-03-2017
DOI: 10.1093/MNRAS/STX562
Publisher: EDP Sciences
Date: 17-12-2002
Publisher: Oxford University Press (OUP)
Date: 12-11-2021
Abstract: Ram pressure stripping (RPS) is an important mechanism for galaxy evolution. In this work, we present results from HST and APEX observations of one RPS galaxy, ESO 137-002 in the closest rich cluster Abell 3627. The galaxy is known to host prominent X-ray and H α tails. The HST data reveal significant features indicative of RPS in the galaxy, including asymmetric distribution of dust in the galaxy, dust filaments, and dust clouds in ablation generally aligned with the direction of ram pressure, and young star clusters immediately upstream of the residual dust clouds that suggest star formation (SF) triggered by RPS. The distribution of the molecular gas is asymmetric in the galaxy, with no CO upstream and abundant CO downstream and in the inner tail region. A total amount of ∼5.5 × 109 M⊙ of molecular gas is detected in the galaxy and its tail. On the other hand, we do not detect any active SF in the X-ray and H α tails of ESO 137-002 with the HST data and place a limit on the SF efficiency in the tail. Hence, if selected by SF behind the galaxy in the optical or UV (e.g. surveys like GASP or using the Galex data), ESO 137-002 will not be considered a ‘jellyfish’ galaxy. Thus, galaxies like ESO 137-002 are important for our comprehensive understanding of RPS galaxies and the evolution of the stripped material. ESO 137-002 also presents a great ex le of an edge-on galaxy experiencing a nearly edge-on RPS wind.
Publisher: Wiley
Date: 13-04-2014
DOI: 10.1111/GEB.12172
Publisher: Oxford University Press (OUP)
Date: 21-12-2012
Publisher: Oxford University Press (OUP)
Date: 28-02-2014
DOI: 10.1093/MNRAS/STU175
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2023
Publisher: Springer Science and Business Media LLC
Date: 04-01-2021
DOI: 10.1007/S10995-021-03315-Z
Abstract: Mother's health and wellbeing significantly affects child health. Women's autonomy can improve healthcare-seeking behaviour, utilisation of healthcare services, and planned pregnancy, thereby improving child health. The global under-five mortality rate (U5MR) has seen the fastest decline in the past two decades, but the influence of gender equality on child mortality remains unaddressed. A strategic approach addressing gender equality is needed to reduce the U5MR further. The study aimed to identify and investigate the association between indicators of gender equality and U5MR using a human rights-based approach. We analysed open-source secondary data from international agencies comprising 521 gender-sensitive variables for 193 countries. Nine variables were included for the final Structural Equation Model based on the theoretical model. Model 1 consisted of 193 countries, and Model 2 comprised a subgroup analysis of 11 variables for 158 countries. Gender equality was a latent variable, and the U5MR was the outcome variable. Gender equality was significantly associated with U5MR (Z = - 7.47, 95% CI = - 754.67 to - 440.98, p < 0‧001, n = 193 for Model 1, and Z = - 7.71, 95% CI = - 808.26 to - 480.72, p < 0‧001, n = 158 for Model 2). Female education, women's waged and salaried employment, women as employers, and women's representation in leadership and parliament enhanced gender equality, whereas the prevalence of child marriage and intimate partner violence (IPV) negatively affected gender equality. Improvement in gender equality significantly reduced U5MR. CONCLUSIONS FOR PRACTICE: Improving women's economic, educational, and social position and increasing female representation in higher leadership and policymaking positions is the key to reducing child mortality. Notably, eliminating child marriage and IPV is the key to achieving gender equality and is needed at the forefront of national policies. Gender equality can significantly improve women's reproductive autonomy, a critical factor in improving healthcare utilisation for women and their children.
Publisher: IOP Publishing
Date: 03-2010
DOI: 10.1086/651535
Publisher: MDPI AG
Date: 29-09-2022
DOI: 10.3390/S22197401
Abstract: Embedding ethical concepts into smart Internet-connected devices and making them behave in a more human-centred manner, i.e., ethically and in a socially acceptable manner, has received significant attention in the software industry. To make smart devices behave in more human-centered manners, it is important to develop a methodology for defining smart devices’ key roles and mapping them with socio-ethical and administrative policies. This paper proposes a policy development methodology for making smart devices more human-centred by following its four phases i.e., concept development, defining and mapping policies, implementing the processing of policies, and deploying the devices. The suggested methodology may be used in a variety of situations where smart devices interact with people. For illustration, the proposed methodology has been applied to three different settings, including a supermarket, a children’s hospital, and early learning centers, where each phase defined in the methodology has been followed. The application of the methodology to smart internet-connected devices, including robots, smart cameras, and smart speakers, has shown significant results. It has been observed that the devices behave in more human-centric ways while performing their core functions, adhering to socio-ethical policies.
Publisher: Oxford University Press (OUP)
Date: 12-10-2020
Abstract: We present the first detection of mass-dependent galactic spin alignments with local cosmic filaments with & σ confidence using IFS kinematics. The 3D network of cosmic filaments is reconstructed on Mpc scales across GAlaxy and Mass Assembly fields using the cosmic web extractor DisPerSe. We assign field galaxies from the SAMI survey to their nearest filament segment in 3D and estimate the degree of alignment between SAMI galaxies’ kinematic spin axis and their nearest filament in projection. Low-mass galaxies align their spin with their nearest filament while higher mass counterparts are more likely to display an orthogonal orientation. The stellar transition mass from the first trend to the second is bracketed between $10^{10.4}$ and $10^{10.9}\\, \\mathrm{ M}_{\\odot }$, with hints of an increase with filament scale. Consistent signals are found in the Horizon-AGN cosmological hydrodynamic simulation. This supports a scenario of early angular momentum build-up in vorticity rich quadrants around filaments at low stellar mass followed by progressive flip of spins orthogonal to the cosmic filaments through mergers at high stellar mass. Conversely, we show that dark matter only simulations post-processed with a semi-analytical model treatment of galaxy formation struggles to reproduce this alignment signal. This suggests that gas physics is key in enhancing the galaxy-filament alignment.
Publisher: Oxford University Press (OUP)
Date: 22-09-2018
Publisher: Oxford University Press (OUP)
Date: 03-05-2017
Publisher: American Astronomical Society
Date: 20-01-2006
DOI: 10.1086/498296
Publisher: Oxford University Press (OUP)
Date: 16-12-2022
Abstract: Observations of the neutral atomic hydrogen (${\\rm H\\, {\\small I}}$) gas in galaxies are predominantly spatially unresolved, in the form of a global ${\\rm H\\, {\\small I}}$ spectral line. There has been substantial work on quantifying asymmetry in global ${\\rm H\\, {\\small I}}$ spectra (‘global ${\\rm H\\, {\\small I}}$ asymmetry’), but due to being spatially unresolved, it remains unknown what physical regions of galaxies the asymmetry traces, and whether the other gas phases are affected. Using optical integral field spectrograph (IFS) observations from the Sydney AAO Multi-object IFS (SAMI) survey for which global ${\\rm H\\, {\\small I}}$ spectra are also available (SAMI-${\\rm H\\, {\\small I}}$), we study the connection between asymmetry in galaxies’ ionized and neutral gas reservoirs to test if and how they can help us better understand the origin of global ${\\rm H\\, {\\small I}}$ asymmetry. We reconstruct the global Hα spectral line from the IFS observations and find that while some global Hα asymmetries can arise from disturbed ionized gas kinematics, the majority of asymmetric cases are driven by the distribution of Hα-emitting gas. When compared to the ${\\rm H\\, {\\small I}}$, we find no evidence for a relationship between the global Hα and ${\\rm H\\, {\\small I}}$ asymmetry. Further, a visual inspection reveals that cases where galaxies have qualitatively similar Hα and ${\\rm H\\, {\\small I}}$ spectral profiles can be spurious, with the similarity originating from an irregular 2D Hα flux distribution. Our results highlight that comparisons between global Hα and ${\\rm H\\, {\\small I}}$ asymmetry are not straightforward, and that many global ${\\rm H\\, {\\small I}}$ asymmetries trace disturbances that do not significantly impact the central regions of galaxies.
Publisher: EDP Sciences
Date: 07-2012
Publisher: EDP Sciences
Date: 2015
Publisher: American Astronomical Society
Date: 2023
Publisher: Oxford University Press (OUP)
Date: 04-08-2023
Abstract: From a purely photometric perspective galaxies are generally decomposed into a bulge+disc system, with bulges being dispersion-dominated and discs rotationally supported. However, recent observations have demonstrated that such a framework oversimplifies complexity, especially if one considers galaxy kinematics. To address this issue we introduced with the GPU-based code bang a novel approach that employs analytical potential-density pairs as galactic components, allowing for a computationally fast, still reliable fit of the morphological and kinematic properties of galaxies. Here we apply bang to the SDSS-MaNGA survey, estimating key parameters such as mass, radial extensions, and dynamics, for both bulges and discs of +10 000 objects. We test our methodology against a smaller subs le of galaxies independently analysed with an orbit-based algorithm, finding agreement in the recovered total stellar mass. We also manage to reproduce well-established scaling relations, demonstrating how proper dynamical modelling can result in tighter correlations and provide corrections to standard approaches. Finally, we propose a more general way of decomposing galaxies into ‘hot’ and ‘cold’ components, showing a correlation with orbit-based approaches and visually determined morphological type. Unexpected tails in the ‘hot-to-total’ mass-ratio distribution are present for galaxies of all morphologies, possibly due to visual morphology misclassifications.
Publisher: Oxford University Press (OUP)
Date: 14-07-2011
Publisher: IOP Publishing
Date: 06-2013
DOI: 10.1086/671138
Publisher: EDP Sciences
Date: 09-2014
Publisher: EDP Sciences
Date: 18-02-2016
Publisher: American Astronomical Society
Date: 09-2022
Abstract: We present new results of a 12 CO( J = 1–0) imaging survey using the Atacama Compact Array (ACA) for 31 H i detected galaxies in the IC 1459 and NGC 4636 groups. This is the first CO imaging survey for loose galaxy groups. We obtained well-resolved CO data (∼0.7–1.5 kpc) for a total of 16 galaxies in two environments. By comparing our ACA CO data with the H i and UV data, we probe the impacts of the group environment on the cold gas components (CO and H i gas) and star formation activity. We find that CO and/or H i morphologies are disturbed in our group members, some of which show highly asymmetric CO distributions (e.g., IC 5264, NGC 7421, and NGC 7418). In comparison with isolated galaxies in the xCOLD GASS s le, our group galaxies tend to have low star formation rates and low H 2 gas fractions. Our findings suggest that the group environment can change the distribution of cold gas components, including the molecular gas and star formation properties of galaxies. This is supporting evidence that preprocessing in the group-like environment can play an important role in galaxy evolution.
Publisher: Cambridge University Press (CUP)
Date: 2023
DOI: 10.1017/PASA.2023.14
Abstract: The quenching of cluster satellite galaxies is inextricably linked to the suppression of their cold interstellar medium (ISM) by environmental mechanisms. While the removal of neutral atomic hydrogen (H i ) at large radii is well studied, how the environment impacts the remaining gas in the centres of galaxies, which are dominated by molecular gas, is less clear. Using new observations from the Virgo Environment traced in CO survey (VERTICO) and archival H i data, we study the H i and molecular gas within the optical discs of Virgo cluster galaxies on 1.2-kpc scales with spatially resolved scaling relations between stellar ( $\\Sigma_{\\star}$ ), H i ( $\\Sigma_{\\text{H}\\,{\\small\\text{I}}}$ ), and molecular gas ( $\\Sigma_{\\text{mol}}$ ) surface densities. Adopting H i deficiency as a measure of environmental impact, we find evidence that, in addition to removing the H i at large radii, the cluster processes also lower the average $\\Sigma_{\\text{H}\\,{\\small\\text{I}}}$ of the remaining gas even in the central $1.2\\,$ kpc. The impact on molecular gas is comparatively weaker than on the H i , and we show that the lower $\\Sigma_{\\text{mol}}$ gas is removed first. In the most H i -deficient galaxies, however, we find evidence that environmental processes reduce the typical $\\Sigma_{\\text{mol}}$ of the remaining gas by nearly a factor of 3. We find no evidence for environment-driven elevation of $\\Sigma_{\\text{H}\\,{\\small\\text{I}}}$ or $\\Sigma_{\\text{mol}}$ in H i -deficient galaxies. Using the ratio of $\\Sigma_{\\text{mol}}$ -to- $\\Sigma_{\\text{H}\\,{\\small\\text{I}}}$ in in idual regions, we show that changes in the ISM physical conditions, estimated using the total gas surface density and midplane hydrostatic pressure, cannot explain the observed reduction in molecular gas content. Instead, we suggest that direct stripping of the molecular gas is required to explain our results.
Publisher: Oxford University Press (OUP)
Date: 30-06-2011
Publisher: Oxford University Press (OUP)
Date: 26-10-2022
Abstract: Gas-phase metallicities of galaxies are typically measured through auroral or nebular emission lines, but metallicity also leaves an imprint on the overall spectral energy distribution (SED) of a galaxy and can be estimated through SED fitting. We use the ProSpect SED fitting code with a flexible parametric star formation history and an evolving metallicity history to self-consistently measure metallicities, stellar mass, and other galaxy properties for $\\sim 90\\, 000$ galaxies from the Deep Extragalactic VIsible Legacy Survey (DEVILS) and Galaxy and Mass Assembly (GAMA) survey. We use these to trace the evolution of the mass–metallicity relation (MZR) and show that the MZR only evolves in normalization by $\\sim 0.1\\,$dex at stellar mass $M_\\star = 10^{10.5}\\, \\mathrm{M}_\\odot$. We find no difference in the MZR between galaxies with and without SED evidence of active galactic nuclei emission at low redshifts ($z$ & 0.3). Our results suggest an anticorrelation between metallicity and star formation activity at fixed stellar mass for galaxies with $M_\\star \\gt 10^{10.5}\\, \\mathrm{M}_\\odot$ for $z$ & 0.3. Using the star formation histories extracted using ProSpect we explore higher order correlations of the MZR with properties of the star formation history including age, width, and shape. We find that at a given stellar mass, galaxies with higher metallicities formed most of their mass over shorter time-scales, and before their peak star formation rate. This work highlights the value of exploring the connection of a galaxy’s current gas-phase metallicity to its star formation history in order to understand the physical processes shaping the MZR.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2019
Publisher: EDP Sciences
Date: 23-03-2012
Publisher: Oxford University Press (OUP)
Date: 07-09-2020
Abstract: The Study of H α from Dwarf Emissions (SHαDE) is a high spectral resolution (R = 13 500) H α integral field survey of 69 dwarf galaxies with stellar masses 106 & M⋆ & 109 M⊙. The survey used FLAMES on the ESO Very Large Telescope. SHαDE is designed to study the kinematics and stellar populations of dwarf galaxies using consistent methods applied to massive galaxies and at matching level of detail, connecting these mass ranges in an unbiased way. In this paper, we set out the science goals of SHαDE, describe the s le properties, outline the data reduction, and analysis processes. We investigate the log M⋆–log S0.5 mass–kinematics scaling relation, which has previously shown potential for combining galaxies of all morphologies in a single scaling relation. We extend the scaling relation from massive galaxies to dwarf galaxies, demonstrating this relation is linear down to a stellar mass of M⋆ ∼ 108.6 M⊙. Below this limit, the kinematics of galaxies inside one effective radius appears to be dominated by the internal velocity dispersion limit of the H α-emitting gas, giving a bend in the log M⋆–log S0.5 relation. Replacing stellar mass with total baryonic mass using gas mass estimate reduces the severity but does not remove the linearity limit of the scaling relation. An extrapolation to estimate the galaxies’ dark matter halo masses, yields a log Mh–log S0.5 scaling relation that is free of any bend, has reduced curvature over the whole mass range, and brings galaxies of all masses and morphologies on to the virial relation.
Publisher: Oxford University Press (OUP)
Date: 14-09-2023
Publisher: American Astronomical Society
Date: 27-07-2005
DOI: 10.1086/444534
Publisher: EDP Sciences
Date: 10-2014
Publisher: Oxford University Press (OUP)
Date: 22-08-2022
Abstract: In this work, we investigate how the central stellar metallicity ([Z/H]) of 1363 galaxies from the SAMI galaxy survey is related to their stellar mass and a proxy for the gravitational potential, $\\Phi = \\log _{10}\\left(\\frac{M_*}{M_{\\odot }} \\right) - \\log _{10}\\left(\\frac{r_e}{\\mathrm{kpc}} \\right)$. In agreement with previous studies, we find that passive and star-forming galaxies occupy different areas of the [Z/H]–M* plane, with passive galaxies having higher [Z/H] than star-forming galaxies at fixed mass (a difference of 0.23 dex at log10(M*/M⊙) = 10.3). We show for the first time that all galaxies lie on the same relation between [Z/H] and Φ, and show that the offset in [Z/H] between passive and star-forming galaxies at fixed Φ is smaller than or equal to the offset in [Z/H] at fixed mass (an average Δ[Z/H] of 0.11 dex at fixed Φ compared to 0.21 dex at fixed mass). We then build a simple model of galaxy evolution to explain and understand our results. By assuming that [Z/H] traces Φ over cosmic time and that the probability that a galaxy quenches depends on both its mass and size, we are able to reproduce these offsets in stellar metallicity with a model containing instantaneous quenching. We therefore conclude that an offset in metallicity at fixed mass cannot by itself be used as evidence of slow quenching processes, in contrast to previous studies. Instead, our model implies that metal-rich galaxies have always been the smallest objects for their mass in a population. Our findings reiterate the need to consider galaxy size when studying stellar populations.
Publisher: EDP Sciences
Date: 07-2010
Publisher: MDPI AG
Date: 20-10-2021
DOI: 10.3390/IOT2040032
Abstract: This paper proposes a policy management framework which we call the SANIJO framework. This framework comprises three different types of policy rules that are applicable to smart devices for managing their multiuser–multidevice interactions in IoT collectives, from a socio-ethical perspective. We developed a policy language to help regulate and manage the interaction behaviors of smart internet-connected devices that are being deployed at an increasing rate around the world. The policy rules are classified into Authorization, Obligation, and Prohibition rules and are prototyped in the SANIJO system. We implemented our framework as a collection of mobile apps (running on smartphones) and a robot app (running on the robot). We then illustrate its operation based on an aged care center scenario.
Publisher: Informa UK Limited
Date: 02-11-2022
Publisher: EDP Sciences
Date: 11-2003
Publisher: Informa UK Limited
Date: 22-03-2018
DOI: 10.1080/09638288.2018.1442504
Abstract: To investigate the relation between observed and perceived upper limb motor function in patients with chronic stroke. We investigated 32 patients at six months after stroke with the Fugl-Meyer Assessment (observed function) and hand subscale of the Stroke Impact Scale (perceived function). Spearman correlation was calculated to relate observed and perceived function. Through cut-off scores, we ided our s le in low (Fugl-Meyer Assessment <31/66) and good observed function, and low (hand subscale of Stroke Impact Scale <61/100) and good perceived function. Scatterplot and hierarchical clustering analysis was conducted to detect distinct groups. A strong positive relation was found between observed and perceived function (r = 0.84). Three groups could be identified a "low match group" of patients with low observed and low perceived function (n = 11, 34%), a "good match group" containing patients with good observed and good perceived function (n = 15, 47%), and a "mismatch group" comprising patients with good observed but low perceived function (n = 6, 19%). In our chronic s le, one in five patients showed good upper limb observed but low perceived function. Measuring both observed and perceived arm and hand function seems warranted together with considering a differential therapy approach for the distinct groups. Implications for rehabilitation A considerable group of patients in the chronic phase post-stroke have good motor function in their affected upper limb, but nevertheless perceive a restricted ability. In order to identify a mismatch in people with chronic stroke, both observed and perceived upper limb motor function should be assessed. Besides common measurement tools for observed function like the Fugl-Meyer Assessment, perceived function can be evaluated by means of the hand function section of the Stroke Impact Scale. For patients with good observed but low perceived function, an additional rehabilitation strategy should be considered, potentially including awareness of ability and a self-efficacy approach.
Publisher: Oxford University Press (OUP)
Date: 03-12-2015
DOI: 10.1093/MNRAS/STS328
Publisher: Wiley
Date: 31-12-2019
DOI: 10.1111/GCB.14904
Abstract: Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to bio ersity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on in idual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
Publisher: EDP Sciences
Date: 06-2014
Publisher: Wiley
Date: 20-01-2014
Publisher: SAGE Publications
Date: 20-05-2021
DOI: 10.1177/10105395211014642
Abstract: This review aimed to investigate national estimates of sugar-sweetened beverage (SSB) consumption in children and adolescents aged two to 18 years, from countries in regions particularly burdened by dietary-related chronic illnesses. The most recent studies or reports from included countries (n = 73) with national-level consumption data of SSBs in children and adolescents, collected between January 2010 and October 2019, were considered for inclusion. A random effects meta-analysis was used to calculate pooled estimates of the mean consumption of SSB in millimeters per day. Heterogeneity between national estimates was assessed using the I 2 statistic and explored via subgroup analyses by the World Health Organization region, age groups, and country-level income. Forty-eight studies were included in the review reporting national estimates of consumption for 51 countries. The highest estimate of daily consumption was in China at 710.0 mL (95% confidence interval (CI) [698.8, 721.2], while the lowest was in Australia at 115.1 mL (95% CI [111.2, 119.1]). Pooled synthesis of daily SSB consumption of the 51 countries was 326.0 mL (95% CI [288.3, 363.8]), although heterogeneity was high, and was not explained by subgroup analyses. While there is considerable variability between countries, intake of SSB remains high among children and adolescents internationally underscoring the need for public health efforts to reduce SSBs consumption.
Publisher: AIP
Date: 2008
DOI: 10.1063/1.2973590
Publisher: Springer Berlin Heidelberg
Date: 25-10-2011
Publisher: American Astronomical Society
Date: 10-11-2006
DOI: 10.1086/507766
Publisher: Oxford University Press (OUP)
Date: 26-04-2016
DOI: 10.1093/MNRAS/STW801
Publisher: American Astronomical Society
Date: 29-10-2014
Publisher: Oxford University Press (OUP)
Date: 05-12-2015
Publisher: Oxford University Press (OUP)
Date: 26-02-2022
Abstract: We investigate the mean locally measured velocity dispersions of ionized gas (σgas) and stars (σ*) for 1090 galaxies with stellar masses $\\log \\, (M_{\\!\\ast }/M_{\\odot }) \\ge 9.5$ from the SAMI Galaxy Survey. For star-forming galaxies, σ* tends to be larger than σgas, suggesting that stars are in general dynamically hotter than the ionized gas (asymmetric drift). The difference between σgas and σ* (Δσ) correlates with various galaxy properties. We establish that the strongest correlation of Δσ is with beam smearing, which inflates σgas more than σ*, introducing a dependence of Δσ on both the effective radius relative to the point spread function and velocity gradients. The second strongest correlation is with the contribution of active galactic nuclei (AGN) (or evolved stars) to the ionized gas emission, implying that the gas velocity dispersion is strongly affected by the power source. In contrast, using the velocity dispersion measured from integrated spectra (σap) results in less correlation between the aperture-based Δσ (Δσap) and the power source. This suggests that the AGN (or old stars) dynamically heat the gas without causing significant deviations from dynamical equilibrium. Although the variation of Δσap is much smaller than that of Δσ, a correlation between Δσap and gas velocity gradient is still detected, implying that there is a small bias in dynamical masses derived from stellar and ionized gas velocity dispersions.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Publisher: Oxford University Press (OUP)
Date: 08-07-2023
Abstract: We present first results from the KMOS Ultra-deep Rotation Velocity Survey (KURVS), aimed at studying the outer rotation curves shape and dark matter content of 22 star-forming galaxies at z ∼ 1.5. These galaxies represent ‘typical’ star-forming discs at z ∼ 1.5, being located within the star-forming main sequence and stellar mass-size relation with stellar masses 9.5 ≤ log(M⋆/M⊙) ≤ 11.5. We use the spatially resolved H α emission to extract in idual rotation curves out to 4 times the effective radius, on average, or ∼10–15 kpc. Most rotation curves are flat or rising between three and six disc scale radii. Only three objects with dispersion-dominated dynamics (vrot/σ0 ∼ 0.2) have declining outer rotation curves at more than 5σ significance. After accounting for seeing and pressure support, the nine rotation-dominated discs with vrot/σ0 ≥ 1.5 have average dark matter fractions of $50 \\pm 20{{\\ \\rm per\\ cent}}$ at the effective radius, similar to local discs. Together with previous observations of star-forming galaxies at cosmic noon, our measurements suggest a trend of declining dark matter fraction with increasing stellar mass and stellar mass surface density at the effective radius. Measurements of simulated EAGLE galaxies are in quantitative agreement with observations up to log$(M_{\\star } R_{\\rm eff}^{-2} /\\mathrm{M_{\\odot } kpc^{-2}}) \\sim 9.2$, and overpredict the dark matter fraction of galaxies with higher mass surface densities by a factor of ∼3. We conclude that the dynamics of typical rotationally-supported discs at z ∼ 1.5 is dominated by dark matter from effective radius scales, in broad agreement with cosmological models. The tension with observations at high stellar mass surface density suggests that the prescriptions for baryonic processes occurring in the most massive galaxies (such as bulge growth and quenching) need to be reassessed.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2018
Publisher: Oxford University Press (OUP)
Date: 23-11-2017
Publisher: EDP Sciences
Date: 08-12-2015
Publisher: Cambridge University Press (CUP)
Date: 2023
DOI: 10.1017/PASA.2023.28
Abstract: We investigate the ersity in the sizes and average surface densities of the neutral atomic hydrogen (H i ) gas discs in $\\sim$ 280 nearby galaxies detected by the Widefield ASKAP L-band Legacy All-sky Blind Survey (WALLABY). We combine the uniformly observed, interferometric H i data from pilot observations of the Hydra cluster and NGC 4636 group fields with photometry measured from ultraviolet, optical, and near-infrared imaging surveys to investigate the interplay between stellar structure, star formation, and H i structural parameters. We quantify the H i structure by the size of the H i relative to the optical disc and the average H i surface density measured using effective and isodensity radii. For galaxies resolved by $ $ $1.3$ beams, we find that galaxies with higher stellar masses and stellar surface densities tend to have less extended H i discs and lower H i surface densities: the isodensity H i structural parameters show a weak negative dependence on stellar mass and stellar mass surface density. These trends strengthen when we limit our s le to galaxies resolved by $ $ 2 beams. We find that galaxies with higher H i surface densities and more extended H i discs tend to be more star forming: the isodensity H i structural parameters have stronger correlations with star formation. Normalising the H i disc size by the optical effective radius (instead of the isophotal radius) produces positive correlations with stellar masses and stellar surface densities and removes the correlations with star formation. This is due to the effective and isodensity H i radii increasing with mass at similar rates while, in the optical, the effective radius increases slower than the isophotal radius. Our results are in qualitative agreement with previous studies and demonstrate that with WALLABY we can begin to bridge the gap between small galaxy s les with high spatial resolution H i data and large, statistical studies using spatially unresolved, single-dish data.
Publisher: Public Library of Science (PLoS)
Date: 08-08-2017
Publisher: Oxford University Press (OUP)
Date: 09-09-2017
Abstract: This work presents a study of galactic outflows driven by stellar feedback. We extract main-sequence disc galaxies with stellar mass 109 ≤ M⋆/ M⊙ ≤ 5.7 × 1010 at redshift z = 0 from the highest resolution cosmological simulation of the Evolution and Assembly of GaLaxies and their Environments (EAGLE) set. Synthetic gas rotation velocity and velocity dispersion (σ) maps are created and compared to observations of disc galaxies obtained with the Sydney-AAO (Australian Astronomical Observatory) Multi-object Integral field spectrograph (SAMI), where σ-values greater than 150 km s−1 are most naturally explained by bipolar outflows powered by starburst activity. We find that the extension of the simulated edge-on (pixelated) velocity dispersion probability distribution depends on stellar mass and star formation rate surface density (ΣSFR), with low-M⋆/low-ΣSFR galaxies showing a narrow peak at low σ (∼30 km s−1) and more active, high-M⋆/high-ΣSFR galaxies reaching σ & 150 km s−1. Although supernova-driven galactic winds in the EAGLE simulations may not entrain enough gas with T & K compared to observed galaxies, we find that gas temperature is a good proxy for the presence of outflows. There is a direct correlation between the thermal state of the gas and its state of motion as described by the σ-distribution. The following equivalence relations hold in EAGLE: (i) low-σ peak ⇔ disc of the galaxy ⇔ gas with T & K (ii) high-σ tail ⇔ galactic winds ⇔ gas with T ≥105 K.
Publisher: Oxford University Press (OUP)
Date: 06-04-2023
Abstract: NGC 5291, an early-type galaxy surrounded by a giant H i ring, is believed to be formed from collision with another galaxy. Several star forming complexes and tidal dwarf galaxies are distributed along the collisional ring which are sites of star formation in environments where extreme dynamical effects are involved. Dynamical effects can affect the star formation properties and the spatial distribution of star forming complexes along the tidal features. To study and quantify the star formation activity in the main body and in the ring structure of the NGC 5291 system, we use high spatial resolution FUV and NUV imaging observations from the Ultraviolet Imaging Telescope onboard AstroSat. A total of 57 star-forming knots are identified to be part of this interacting system out of which 12 are new detections (star forming complexes that lie inside the H i contour) compared to the previous measurements from lower resolution UV imaging. We estimate the attenuation in UV for each of the resolved star-forming knots using the UV spectral slope β, derived from the FUV − NUV colour. Using the extinction corrected UV fluxes, we derive the star formation rate of the resolved star forming complexes. The extinction corrected total star formation rate of this system is estimated as 1.75 ± 0.04 $\\mathrm{M_\\odot \\, yr}^{-1}$. The comparison with dwarf galaxy populations (BCD, Sm, and dIm galaxies) in the nearby Universe shows that many of the knots in the NGC 5291 system have SFR values comparable to the SFR of BCD galaxies.
Publisher: EDP Sciences
Date: 06-2018
DOI: 10.1051/0004-6361/201732373
Abstract: The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) is a blind narrow-band H α + [NII] imaging survey carried out with MegaCam at the Canada-France-Hawaii Telescope. During pilot observations taken in the spring of 2016 we observed NGC 4330, an intermediate mass ( M * ≃ 10 9.8 M ⊙ ) edge-on star forming spiral currently falling into the core of the Virgo cluster. While previous H α observations showed a clumpy complex of ionised gas knots outside the galaxy disc, new deep observations revealed a low surface brightness ~10 kpc tail exhibiting a peculiar filamentary structure. The filaments are remarkably parallel to one another and clearly indicate the direction of motion of the galaxy in the Virgo potential. Motivated by the detection of these features which indicate ongoing gas stripping, we collected literature photometry in 15 bands from the far-UV to the far-IR and deep optical long-slit spectroscopy using the FORS2 instrument at the ESO Very Large Telescope. Using a newly developed Monte Carlo code that jointly fits spectroscopy and photometry, we reconstructed the star formation histories in apertures along the major axis of the galaxy. Our results have been validated against the output of CIGALE, a fitting code which has been previously used for similar studies. We found a clear outside-in gradient with radius of the time when the quenching event started: the outermost radii were stripped ~500 Myr ago, while the stripping reached the inner 5 kpc from the centre in the last 100 Myr. Regions at even smaller radii are currently still forming stars fueled by the presence of HI and H 2 gas. When compared to statistical studies of the quenching timescales in the local Universe we find that ram pressure stripping of the cold gas is an effective mechanism to reduce the transformation times for galaxies falling into massive clusters. Future systematic studies of all the active galaxies observed by VESTIGE in the Virgo cluster will extend these results to a robust statistical framework.
Publisher: American Astronomical Society
Date: 18-03-2005
DOI: 10.1086/429377
Publisher: EDP Sciences
Date: 09-2012
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-08-2022
DOI: 10.36227/TECHRXIV.20445015
Abstract: This article is under review and upon acceptance: Personal use of this material is permitted. However, permission to use this material for any other purposes must be obtained from the IEEE by sending a request to pubs-permissions@ieee.org. (Copyright (c) 2015 IEEE.)
Publisher: Oxford University Press (OUP)
Date: 10-2006
Publisher: Oxford University Press (OUP)
Date: 31-08-2018
Publisher: Cambridge University Press (CUP)
Date: 07-2014
DOI: 10.1017/S1743921314009740
Abstract: For the first time in any ram pressure stripped galaxy, we detect large amounts of cold molecular gas in the X-ray bright, and star forming tail of ESO 137-001 in the Norma cluster. We find very low star formation efficiency in the stripped gas, similar to values found in the outer spiral disks where however molecular gas is mostly undetected. The results were recently published in Jáchym et al . (2014).
Publisher: Wiley
Date: 04-09-2009
Publisher: Oxford University Press (OUP)
Date: 24-06-2011
Publisher: ACM
Date: 27-03-2023
Publisher: Copernicus GmbH
Date: 30-11-2018
Abstract: Abstract. Inland waters are large contributors to global carbon dioxide (CO2) emissions, in part due to the vulnerability of dissolved organic matter (DOM) to microbial decomposition and respiration to CO2 during transport through aquatic systems. To assess the degree of this vulnerability, aquatic DOM is often incubated in standardized biolability assays. These assays isolate the dissolved fraction of aquatic OM by size filtration prior to incubation. We test whether this size selection has an impact on the bacterial community composition and the consequent dynamics of DOM degradation using three different filtration strategies: 0.2 µm (filtered and inoculated), 0.7 µm (generally the most common DOM filter size) and 106 µm (unfiltered). We found that bacterial community composition, based on 16S rRNA licon sequencing, was significantly affected by the different filter sizes. At the same time, the filtration strategy also affected the DOM degradation dynamics, including the δ13C signature. However, the dynamics of these two responses were decoupled, suggesting that filtration primarily influences biolability assays through bacterial abundance and the presence of their associated predators. By the end of the 41-day incubations all treatments tended to converge on a common total DOM biolability level, with the 0.7 µm filtered incubations reaching this point the quickest. These results suggest that assays used to assess the total biolability of aquatic DOM should last long enough to remove filtration artefacts in the microbial population. Filtration strategy should also be taken into account when comparing results across biolability assays.
Publisher: Oxford University Press (OUP)
Date: 24-06-2011
Publisher: American Astronomical Society
Date: 11-2003
DOI: 10.1086/378264
Publisher: Oxford University Press (OUP)
Date: 12-01-2018
DOI: 10.1093/MNRAS/STY089
Publisher: Oxford University Press (OUP)
Date: 02-02-2015
Publisher: EDP Sciences
Date: 25-10-2011
Publisher: Oxford University Press (OUP)
Date: 25-07-2019
Abstract: Using a spectral stacking technique, we measure the neutral hydrogen (H i) properties of a s le of galaxies at z 0.11 across 35 pointings of the Westerbork Synthesis Radio Telescope. The radio data contain 1895 galaxies with redshifts and positions known from the Sloan Digital Sky Survey. We carefully quantified the effects of s le bias, aperture used to extract spectra, sidelobes and weighting technique and use our data to provide a new estimate for the cosmic H i mass density. We find a cosmic H i mass density of $\\Omega _{\\rm H\\,{\\small I}} = (4.02 \\pm 0.26)\\times 10^{-4} h_{70}^{-1}$ at 〈z〉 = 0.066, consistent with measurements from blind H i surveys and other H i stacking experiments at low redshifts. The combination of the small interferometer beam size and the large survey volume makes our result highly robust against systematic effects due to confusion at small scales and cosmic variance at large scales. Splitting into three sub-s les with 〈z〉 = 0.038, 0.067, and 0.093 shows no significant evolution of the H i gas content at low redshift.
Publisher: Oxford University Press (OUP)
Date: 11-07-2014
Publisher: American Astronomical Society
Date: 26-03-2018
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2015
DOI: 10.1161/STROKEAHA.115.009421
Abstract: Recovery of patients within the first 6 months after stroke is well documented, but there has been little research on long-term recovery. The aim of this study was to analyze functional and motor recovery between admission to rehabilitation centres and 5 years after stroke. This follow-up of the Collaborative Evaluation of Rehabilitation in Stroke Across Europe study, included patients from 4 European rehabilitation centres. Patients were assessed on admission, at 2 and 6 months, and 5 years after stroke, using the Barthel Index, Rivermead Motor Assessment Gross Function, Leg and Trunk function, and Arm function. Linear mixed models were used, corrected for baseline characteristics. To account for the drop-out during follow-up, the analysis is likelihood-based (assumption of missingness at random). A total of 532 patients were included in this study, of which 238 were followed up at 5 years post stroke. Mean age at stroke onset was 69 (±10 SD) years, 53% were men, 84% had ischemic strokes, and 53% had left-sided motor impairment. Linear mixed model analysis revealed a significant deterioration for all 4 outcomes between 6 months and 5 years ( P .0001). Scores at 2 months were not statistically significant different from scores at 5 years after stroke. Higher age ( P .0001) and increasing stroke severity on admission ( P .0001) negatively affected long-term functional and motor recovery. Five-year follow-up revealed deterioration in functional and motor outcome, with a return to the level measured at 2 months. Increasing age and increasing stroke severity negatively affected recovery up to 5 years after stroke.
Publisher: Oxford University Press (OUP)
Date: 22-11-2011
Publisher: Oxford University Press (OUP)
Date: 14-07-2016
Publisher: Oxford University Press (OUP)
Date: 13-10-2015
Publisher: MDPI AG
Date: 27-10-2023
DOI: 10.3390/S23218779
Publisher: Oxford University Press (OUP)
Date: 21-08-2023
Publisher: Cambridge University Press (CUP)
Date: 2022
DOI: 10.1017/PASA.2022.50
Abstract: We present WALLABY pilot data release 1, the first public release of H i pilot survey data from the Wide-field ASKAP L-band Legacy All-sky Blind Survey (WALLABY) on the Australian Square Kilometre Array Pathfinder. Phase 1 of the WALLABY pilot survey targeted three $60\\,\\mathrm{deg}^{2}$ regions on the sky in the direction of the Hydra and Norma galaxy clusters and the NGC 4636 galaxy group, covering the redshift range of $z \\lesssim 0.08$ . The source catalogue, images and spectra of nearly 600 extragalactic H i detections and kinematic models for 109 spatially resolved galaxies are available. As the pilot survey targeted regions containing nearby group and cluster environments, the median redshift of the s le of $z \\approx 0.014$ is relatively low compared to the full WALLABY survey. The median galaxy H i mass is $2.3 \\times 10^{9}\\,{\\rm M}_{{\\odot}}$ . The target noise level of $1.6\\,\\mathrm{mJy}$ per 30 ′′ beam and $18.5\\,\\mathrm{kHz}$ channel translates into a $5 \\sigma$ H i mass sensitivity for point sources of about $5.2 \\times 10^{8} \\, (D_{\\rm L} / \\mathrm{100\\,Mpc})^{2} \\, {\\rm M}_{{\\odot}}$ across 50 spectral channels ( ${\\approx} 200\\,\\mathrm{km \\, s}^{-1}$ ) and a $5 \\sigma$ H i column density sensitivity of about $8.6 \\times 10^{19} \\, (1 + z)^{4}\\,\\mathrm{cm}^{-2}$ across 5 channels ( ${\\approx} 20\\,\\mathrm{km \\, s}^{-1}$ ) for emission filling the 30 ′′ beam. As expected for a pilot survey, several technical issues and artefacts are still affecting the data quality. Most notably, there are systematic flux errors of up to several 10% caused by uncertainties about the exact size and shape of each of the primary beams as well as the presence of sidelobes due to the finite deconvolution threshold. In addition, artefacts such as residual continuum emission and bandpass ripples have affected some of the data. The pilot survey has been highly successful in uncovering such technical problems, most of which are expected to be addressed and rectified before the start of the full WALLABY survey.
Publisher: Springer Berlin Heidelberg
Date: 25-10-2011
Publisher: Oxford University Press (OUP)
Date: 15-09-2021
Abstract: The kinematic morphology–density relation of galaxies is normally attributed to a changing distribution of galaxy stellar masses with the local environment. However, earlier studies were largely focused on slow rotators the dynamical properties of the overall population in relation to environment have received less attention. We use the SAMI Galaxy Survey to investigate the dynamical properties of ∼1800 early and late-type galaxies with log (M⋆/M⊙) & 9.5 as a function of mean environmental overdensity (Σ5) and their rank within a group or cluster. By classifying galaxies into fast and slow rotators, at fixed stellar mass above log (M⋆/M⊙) & 10.5, we detect a higher fraction (∼3.4σ) of slow rotators for group and cluster centrals and satellites as compared to isolated-central galaxies. We find similar results when using Σ5 as a tracer for environment. Focusing on the fast-rotator population, we also detect a significant correlation between galaxy kinematics and their stellar mass as well as the environment they are in. Specifically, by using inclination-corrected or intrinsic $\\lambda _{R_{\\rm {e}}}$ values, we find that, at fixed mass, satellite galaxies on average have the lowest $\\lambda _{\\, R_{\\rm {e}},\\rm {intr}}$, isolated-central galaxies have the highest $\\lambda _{\\, R_{\\rm {e}},\\rm {intr}}$, and group and cluster centrals lie in between. Similarly, galaxies in high-density environments have lower mean $\\lambda _{\\, R_{\\rm {e}},\\rm {intr}}$ values as compared to galaxies at low environmental density. However, at fixed Σ5, the mean $\\lambda _{\\, R_{\\rm {e}},\\rm {intr}}$ differences for low and high-mass galaxies are of similar magnitude as when varying Σ5 ($\\Delta \\lambda _{\\, R_{\\rm {e}},\\rm {intr}} \\sim 0.05$, with σrandom = 0.025, and σsyst & 0.03). Our results demonstrate that after stellar mass, environment plays a significant role in the creation of slow rotators, while for fast rotators we also detect an independent, albeit smaller, impact of mass and environment on their kinematic properties.
Publisher: EDP Sciences
Date: 09-2018
DOI: 10.1051/0004-6361/201832873
Abstract: Aims. We discuss the results of the relationships between the K -band and stellar mass, FIR luminosities, star formation rate, and the masses of the dust and gas of nearby galaxies computing the bivariate K -band-luminosity function (BLF) and bivariate K -band-mass function (BMF) of the Herschel Reference Survey (HRS), a volume-limited s le with full wavelength coverage. Methods. We derive the BLFs and BMFs from the K -band and stellar mass, FIR luminosities, star formation rate, dust and gas masses cumulative distributions using a copula method, which is outlined in detail. The use of the computed bivariate taking into account the upper limits allows us to derive a more solid statistical ground for the relationship between the observed physical quantities. Results. The analysis shows that the behaviour of the morphological (optically selected) subs les is quite different. A statistically meaningful result can be obtained over the whole HRS s le only from the relationship between the K -band and the stellar mass, while for the remaining physical quantities (dust and gas masses, far-infrared luminosity, and star formation rate), the analysis is distinct for late-type (LT) and early-type galaxies (ETG). However, the number of ETGs is small to perform a robust statistical analysis, and in most of the case results are discussed only for the LTG subs le. The luminosity and mass functions (LFs, MFs) of LTGs are generally dependent on the K -band and the various dependencies are discussed in detail. We are able to derive the corresponding LFs and MFs and compare them with those computed with other s les. Our statistical analysis allows us to characterise the HRS which, although non-homogeneously selected and partially biased towards low IR luminosities, may be considered as representative of the local LT galaxy population.
Publisher: American Astronomical Society
Date: 28-12-2018
Publisher: EDP Sciences
Date: 26-03-2012
Publisher: American Astronomical Society
Date: 02-2021
Abstract: We study the stellar and gas kinematics of the brightest group galaxies (BGGs) in dynamically relaxed and unrelaxed galaxy groups for a s le of 154 galaxies in the SAMI galaxy survey. We characterize the dynamical state of the groups using the luminosity gap between the two most luminous galaxies and the BGG offset from the luminosity centroid of the group. We find that the misalignment between the rotation axis of gas and stellar components is more frequent in the BGGs in unrelaxed groups, although with quite low statistical significance. Meanwhile, galaxies whose stellar dynamics would be classified as “regular rotators” based on their kinemetry are more common in relaxed groups. We confirm that this dependency on group dynamical state remains valid at fixed stellar mass and Sérsic index. The observed trend could potentially originate from a differing BGG accretion history in virialized and evolving groups. Among the halo relaxation probes, the group BGG offset appears to play a stronger role than the luminosity gap on the stellar kinematic differences of the BGGs. However, both the group BGG offset and luminosity gap appear to roughly equally drive the misalignment between the gas and stellar component of the BGGs in one direction. This study offers the first evidence that the dynamical state of galaxy groups may influence the BGG's stellar and gas kinematics, and we call for further studies using a larger s le with higher signal-to-noise.
Publisher: Elsevier BV
Date: 12-2018
DOI: 10.1016/J.APMR.2018.04.025
Abstract: To investigate interrater and intrarater reliability, measurement error, and convergent and discriminative validity of the Adult Assisting Hand Assessment Stroke (Ad-AHA Stroke). Cross-sectional observational study. A total of 7 stroke rehabilitation centers. Stroke survivors (reliability s le: n=30 validity s le: N=118) were included (median age 67y interquartile range [IQR], 59-76) median time poststroke 81 days (IQR 57-117). N/A. Ad-AHA Stroke, Action Research Arm Test (ARAT), upper extremity Fugl-Meyer Assessment (UE-FMA). The Ad-AHA Stroke is an observation-based instrument assessing the effectiveness of the spontaneous use of the affected hand when performing bimanual activities in adults poststroke. Reliability of Ad-AHA Stroke was examined using intraclass correlation coefficients (ICCs), Bland-Altman plots, and weighted kappa statistics for reliability on item level. SEM was calculated based on Ad-AHA units. Convergent validity was assessed by calculating Spearman rank correlation coefficients between Ad-AHA Stroke and ARA test and UE-FMA. Comparison of Ad-AHA Stroke scores between subgroups of patients according to hand dominance, neglect, and age evaluated discriminative validity. Intrarater and interrater agreement showed an ICC of 0.99 (95% confidence interval, 0.99-0.99), an SEM of 2.15 and 1.64 out of 100, respectively, and weighted kappa for item scores were all above 0.79. The relation between Ad-AHA and other clinical assessments was strong (ρ=0.9). Patients with neglect had significantly lower Ad-AHA scores compared to patients without neglect (P=.004). The Ad-AHA Stroke captures actual bimanual performance. Therefore, it provides an additional aspect of upper limb assessment with good to excellent reliability and low SEM for patients with subacute stroke. High convergent validity with the ARA test and UE-FMA and discriminative validity were supported.
Publisher: Oxford University Press (OUP)
Date: 07-11-2016
Publisher: Wiley
Date: 09-2012
DOI: 10.1002/PRI.1535
Publisher: MDPI AG
Date: 02-2023
DOI: 10.3390/JSAN12010012
Abstract: Currently, many governments are gearing up to promote the development of smart cities in their countries. A smart city is an urban area using different types of sensors to collect data, which will then be used to manage assets and resources efficiently. Through smart technology, the quality of living and performance of urban services are enhanced. Recent works addressed a set of platforms aimed to support the development of smart city applications. It seems that most of them involved dealing with collecting, managing, analyzing, and correlating data to extract new information useful to a city, but they do not integrate a ersified set of services and react to events on the fly. Moreover, the application development facilities provided by them seem to be limited and might even increase the complexity of this task. We propose an event-based architecture with components that meet important requirements for smart city platforms, supporting increased demand for scalability, flexibility, and heterogeneity in event processing. We implement such architecture and data representation models, handling different data formats, and supporting a semantics-based data model. Finally, we discuss the effectiveness of a S mart Event-based Middleware (SEMi) and present empirical results regarding a performance evaluation of SEMi.
Publisher: Oxford University Press (OUP)
Date: 21-03-2009
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2019
Publisher: Public Library of Science (PLoS)
Date: 12-10-2018
Publisher: EDP Sciences
Date: 03-2022
DOI: 10.1051/0004-6361/202142482
Abstract: As part of the Virgo Cluster Survey Tracing Ionised Gas Emission, a blind narrow-band H α +[NII] imaging survey of the Virgo cluster carried out with MegaCam at the CFHT, we discovered eight massive (10 10 ≲ M star ≲ 10 11 M ⊙ ) lenticular galaxies with prominent ionised gas emission features in their inner (a few kiloparsec) regions. These features are either ionised gas filaments similar to those observed in cooling flows (two galaxies), or they are thin discs with sizes 0.7 ≲ R (H α )≲2.0 kpc (six galaxies), thus significantly smaller than those of the stellar disc ( R (H α )≃7 − 22% R iso ( r )). The morphological properties of these discs are similar to those of the dust seen in absorption in high-resolution HST images. Using a unique set of multifrequency data, including new or archival ASTROSAT/UVIT, GALEX, HST, CFHT, Spitzer , and Herschel imaging data, combined with IFU (MUSE, ALMA) and long-slit (SOAR) spectroscopy, we show that while the gas that is located within these inner discs is photoionised by young stars, which signals ongoing star formation, the gas in the filamentary structures is shock ionised. The star formation surface brightness of these discs is similar to that observed in late-type galaxies. Because of their reduced size, however, these lenticular galaxies are located below the main sequence of unperturbed or cluster star-forming systems. By comparing the dust masses measured from absorption maps in optical images, from the Balmer decrement, or estimated by fitting the UV-to-far-IR spectral energy distribution of the target galaxies, we confirm that the dust masses derived from optical attenuation maps are heavily underestimated because of geometrical effects due to the relative distribution of the absorbing dust and the emitting stars. We also show that these galaxies have gas-to-dust ratios of G / D ≃ 80 30 320 , and that the star formation within these discs follows the Schmidt relation, but with an efficiency that is reduced by a factor of ∼2.5. Using our unique set of multifrequency data, we discuss the possible origin of the ionised gas in these objects, which suggests multiple and complex formation scenarios for massive lenticular galaxies in clusters.
Publisher: MDPI AG
Date: 24-06-2022
DOI: 10.3390/S22134795
Abstract: The smart grid is one of the core technologies that enable sustainable economic and social developments. In recent years, various cyber attacks have targeted smart grid systems, which have led to severe, harmful consequences. It would be challenging to build a real smart grid system for cybersecurity experimentation and validation purposes. Hence, analytical techniques, with simulations, can be considered as a practical solution to make smart grid cybersecurity experimentation possible. This paper first provides a literature review on the current state-of-the-art in smart grid attack analysis. We then apply graphical security modeling techniques to design and implement a Cyber Attack Analysis Framework for Smart Grids, named GridAttackAnalyzer. A case study with various attack scenarios involving Internet of Things (IoT) devices is conducted to validate the proposed framework and demonstrate its use. The functionality and user evaluations of GridAttackAnalyzer are also carried out, and the evaluation results show that users have a satisfying experience with the usability of GridAttackAnalyzer. Our modular and extensible framework can serve multiple purposes for research, cybersecurity training, and security evaluation in smart grids.
Publisher: EDP Sciences
Date: 27-02-2023
DOI: 10.1051/0004-6361/202244718
Abstract: Aims. In this Virgo Environment Traced in CO (VERTICO) science paper, we aim to study how the star formation process depends on the galactic environment and gravitational interactions in the context of galaxy evolution. We explore the scaling relation between the star formation rate surface density (Σ SFR ) and the molecular gas surface density (Σ mol ), also known as the Kennicutt-Schmidt relation, in a subs le of Virgo cluster spiral galaxies. Methods. We used new Atacama Compact Array and Total Power (ACA+TP) observations from the VERTICO-Atacama Large Millimeter/submillimeter Array (ALMA) Large Program at 720 pc resolution to resolve the molecular gas content, as traced by the 12 CO (2 − 1) transition, across the disks of 37 spiral galaxies in the Virgo cluster. In combination with archival UV and IR observations used to determine the star formation rate (SFR), we estimated the parameters of the Kennicutt-Schmidt (KS) relation for the entire ensemble of galaxies, and within in idual galaxies. Results. We find the KS slope for the entire population to be N = 0.97 ± 0.07, with a characteristic molecular gas depletion time of 1.86 Gyr for our full s le, which is in agreement with previous work in isolated, nearby star-forming galaxies. In in idual galaxies, we find that the KS slope ranges between 0.69 and 1.40, and that typical star formation efficiencies of molecular gas can vary from galaxy to galaxy by a factor of ∼4. These galaxy-to-galaxy variations account for ∼0.20 dex in scatter in the ensemble KS relation, which is characterized by a 0.42 dex scatter. In addition, we find that the HI-deficient galaxies in the Virgo cluster show a steeper resolved KS relation and lower molecular gas efficiencies than HI-normal cluster galaxies. Conclusions. While the molecular gas content in galaxies residing in the Virgo cluster appears – to first order – to behave similarly to that in isolated galaxies, our VERTICO s le of galaxies shows that cluster environments play a key role in regulating star formation. The environmental mechanisms affecting the HI galaxy content also have a direct impact on the star formation efficiency of molecular gas in cluster galaxies, leading to longer depletion times in HI-deficient members.
Publisher: Oxford University Press (OUP)
Date: 11-2021
Abstract: We use a s le of z = 0 galaxies visually classified as slow rotators (SRs) in the eagle hydrodynamical simulations to explore the effect of galaxy mergers on their formation, characterize their intrinsic galaxy properties, and study the connection between quenching and kinematic transformation. SRs that have had major or minor mergers (mass ratios ≥0.3 and 0.1−0.3, respectively) tend to have a higher triaxiality parameter and ex-situ stellar fractions than those that had exclusively very minor mergers or formed in the absence of mergers (‘no-merger’ SRs). No-merger SRs are more compact, have lower black hole-to-stellar mass ratios and quenched later than other SRs, leaving imprints on their z = 0 chemical composition. For the vast majority of SRs we find that quenching, driven by active galactic nuclei feedback, precedes kinematic transformation, except for satellite SRs, in which these processes happen in tandem. However, in ≈50 per cent of these satellites, satellite–satellite mergers are responsible for their SR fate, while environment (i.e. tidal field and interactions with the central) can account for the transformation in the rest. By splitting SRs into kinematic sub-classes, we find that flat SRs prefer major mergers round SRs prefer minor or very minor mergers prolate SRs prefer gas-poor mergers. Flat and prolate SRs are more common among satellites hosted by massive haloes ($\\gt 10^{13.6}\\, \\rm M_{\\odot }$) and centrals of high masses ($M_{\\star } \\gt 10^{10.5}\\, \\rm M_{\\odot }$). Although eagle galaxies display kinematic properties that broadly agree with observations, there are areas of disagreement, such as inverted stellar age and velocity dispersion profiles. We discuss these and how upcoming simulations can solve them.
Publisher: American Astronomical Society
Date: 14-07-2015
Publisher: Oxford University Press (OUP)
Date: 21-02-2020
Abstract: Recent studies of neutral atomic hydrogen (H i) in nearby galaxies found that all field disc galaxies are H i saturated, in that they carry roughly as much H i as permitted before this gas becomes gravitationally unstable. By taking this H i saturation for granted, the atomic gas fraction fatm of galactic discs can be predicted as a function of the stability parameter q = jσ/(GM), where M and j are the baryonic mass and specific angular momentum of the disc and σ is the H i velocity dispersion (Obreschkow et al. 2016). The log-ratio Δfq between this predictor and the observed atomic fraction can be seen as a physically motivated ‘H i deficiency’. While field disc galaxies have Δfq ≈ 0, objects subject to environmental removal of H i are expected to have Δfq & 0. Within this framework, we revisit the H i deficiencies of satellite galaxies in the Virgo cluster and in clusters of the EAGLE simulation. We find that observed and simulated cluster galaxies are H i deficient and that Δfq slightly increases when getting closer to the cluster centres. The Δfq values are similar to traditional H i deficiency estimators, but Δfq is more directly comparable between observations and simulations than morphology-based–deficiency estimators. By tracking the simulated H i deficient cluster galaxies back in time, we confirm that Δfq ≈ 0 until the galaxies first enter a halo with $M_{\\rm halo}\\gt 10^{13}\\rm M_{\\odot }$, at which moment they quickly lose H i by environmental effects. Finally, we use the simulation to investigate the links between Δfq and quenching of star formation.
Publisher: Oxford University Press (OUP)
Date: 14-05-2018
Publisher: EDP Sciences
Date: 05-2014
Publisher: American Astronomical Society
Date: 10-2023
Publisher: EDP Sciences
Date: 07-2015
Publisher: American Astronomical Society
Date: 2021
Abstract: We explore stellar population properties separately in the bulge and the disk of double-component cluster galaxies, to shed light on the formation of lenticular galaxies in dense environments. We study eight low-redshift clusters from the Sydney-AAO Multi-object Integral field Galaxy Survey, using two-dimensional photometric bulge–disk decomposition in the g , r , and i bands to characterize galaxies. For 192 double-component galaxies with M * 10 10 M ⊙ , we estimate the color, age, and metallicity of the bulge and the disk. The analysis of the g − i colors reveals that bulges are redder than their surrounding disks, with a median offset of 0.12 ± 0.02 mag, consistent with previous results. To measure mass-weighted age and metallicity, we investigate three methods: (i) one based on galaxy stellar mass weights for the two components, (ii) one based on flux weights, and (iii) one based on radial separation. The three methods agree in finding 62% of galaxies having bulges that are 2–3 times more metal-rich than the disks. Of the remaining galaxies, 7% have bulges that are more metal-poor than the disks, while for 31%, the bulge and disk metallicities are not significantly different. We observe 23% of galaxies being characterized by bulges older and 34% by bulges younger with respect to the disks. The remaining 43% of galaxies have bulges and disks with statistically indistinguishable ages. Redder bulges tend to be more metal-rich than the disks, suggesting that the redder color in bulges is due to their enhanced metallicity relative to the disks instead of differences in stellar population age.
Publisher: MDPI AG
Date: 04-07-2021
DOI: 10.3390/IOT2030021
Abstract: The Internet of Things is emerging as a vast, inter-connected space of devices and things surrounding people, many of which are increasingly capable of autonomous action, from automatically sending data to cloud servers for analysis, changing the behaviour of smart objects, to changing the physical environment. A wide range of ethical concerns has arisen in their usage and development in recent years. Such concerns are exacerbated by the increasing autonomy given to connected things. This paper reviews, via ex les, the landscape of ethical issues, and some recent approaches to address these issues concerning connected things behaving autonomously as part of the Internet of Things. We consider ethical issues in relation to device operations and accompanying algorithms. Ex les of concerns include unsecured consumer devices, data collection with health-related Internet of Things, hackable vehicles, behaviour of autonomous vehicles in dilemma situations, accountability with Internet of Things systems, algorithmic bias, uncontrolled cooperation among things, and automation affecting user choice and control. Current ideas towards addressing a range of ethical concerns are reviewed and compared, including programming ethical behaviour, white-box algorithms, black-box validation, algorithmic social contracts, enveloping IoT systems, and guidelines and code of ethics for IoT developers a suggestion from the analysis is that a multi-pronged approach could be useful based on the context of operation and deployment.
Publisher: EDP Sciences
Date: 28-06-2006
Publisher: Cambridge University Press (CUP)
Date: 2021
DOI: 10.1017/PASA.2021.18
Abstract: One of the key open questions in extragalactic astronomy is what stops star formation in galaxies. While it is clear that the cold gas reservoir, which fuels the formation of new stars, must be affected first, how this happens and what are the dominant physical mechanisms involved is still a matter of debate. At least for satellite galaxies, it is generally accepted that internal processes alone cannot be responsible for fully quenching their star formation, but that environment should play an important, if not dominant, role. In nearby clusters, we see ex les of cold gas being removed from the star-forming discs of galaxies moving through the intracluster medium, but whether active stripping is widespread and/or necessary to halt star formation in satellites, or quenching is just a consequence of the inability of these galaxies to replenish their cold gas reservoirs, remains unclear. In this work, we review the current status of environmental studies of cold gas in star-forming satellites in the local Universe from an observational perspective, focusing on the evidence for a physical link between cold gas stripping and quenching of the star formation. We find that stripping of cold gas is ubiquitous in satellite galaxies in both group and cluster environments. While hydrodynamical mechanisms such as ram pressure are important, the emerging picture across the full range of dark matter halos and stellar masses is a complex one, where different physical mechanisms may act simultaneously and cannot always be easily separated. Most importantly, we show that stripping does not always lead to full quenching, as only a fraction of the cold gas reservoir might be affected at the first pericentre passage. We argue that this is a key point to reconcile apparent tensions between statistical and detailed analyses of satellite galaxies, as well as disagreements between various estimates of quenching timescales. We conclude by highlighting several outstanding questions where we expect to see substantial progress in the coming decades, thanks to the advent of the Square Kilometre Array and its precursors, as well as the next-generation optical and millimeter facilities.
Publisher: Oxford University Press (OUP)
Date: 08-08-2016
Publisher: Oxford University Press (OUP)
Date: 10-01-2018
DOI: 10.1093/MNRAS/STY063
Publisher: Oxford University Press (OUP)
Date: 17-01-2020
Abstract: We present an analysis of asymmetries in global H i spectra from the extended GALEX Arecibo SDSS Survey (xGASS), a stellar mass-selected and gas fraction-limited survey which is representative of the H i properties of galaxies in the local Universe. We demonstrate that the asymmetry in a H i spectrum is strongly linked to its signal-to-noise meaning that, contrary to what was done in previous works, asymmetry distributions for different s les cannot be compared at face value. We develop a method to account for noise-induced asymmetry and find that the typical galaxy detected by xGASS exhibits higher asymmetry than what can be attributed to noise alone, with 37 per cent of the s le showing asymmetry greater than 10 per cent at an 80 per cent confidence level. We find that asymmetric galaxies contain, on average, 29 per cent less H i mass compared to their symmetric counterparts matched in both stellar mass and signal-to-noise. We also present clear evidence that satellite galaxies, as a population, exhibit more asymmetric H i spectra than centrals and that group central galaxies show a slightly higher rate of H i asymmetries compared to isolated centrals. All these results support a scenario in which environmental processes, in particular those responsible for gas removal, are the dominant driver of asymmetry in xGASS.
Publisher: EDP Sciences
Date: 10-2012
Publisher: Wiley
Date: 15-10-2008
Publisher: Oxford University Press (OUP)
Date: 15-10-2020
Abstract: Observations of the cold neutral atomic hydrogen (H i) in and around disc galaxies have revealed that spatial and kinematic asymmetries are common place, and are reflected in the global H i spectra. We use the TNG100 box from the IllustrisTNG suite of cosmological simulations to study the conditions under which these asymmetries may arise in current theoretical galaxy formation models. We find that more than 50 per cent of the s le has at least a 10 per cent difference in integrated flux between the high- and low-velocity half of the spectrum, thus the typical TNG100 galaxy has an H i profile that is not fully symmetric. We find that satellite galaxies are a more asymmetric population than centrals, consistent with observational results. Using halo mass as a proxy for environment, this trend appears to be driven by the satellite population within the virial radius of haloes more massive than 1013 M⊙, typical of medium/large groups. We show that, while the excess of H i asymmetry in group satellites is likely driven by ram pressure, the bulk of the asymmetric H i profiles observed in TNG100 are driven by physical processes able to affect both the central and satellite populations. Our results highlight how asymmetries are not driven solely by environment, and multiple physical processes can produce the same asymmetric shape in global H i spectra.
Publisher: Oxford University Press (OUP)
Date: 16-03-2022
Abstract: We investigate changes in stellar population age and metallicity ([Z/H]) scaling relations for quiescent galaxies from intermediate redshift (0.60 ≤ $z$ ≤ 0.76) using the LEGA-C Survey to low redshift (0.014 ≤ $z$ ≤ 0.10) using the SAMI Galaxy Survey. Specifically, we study how the spatially integrated global age and metallicity of in idual quiescent galaxies vary in the mass–size plane, using the stellar mass M* and a dynamical mass proxy derived from the virial theorem MD ∝ σ2 Re. We find that, similarly to at low redshift, the metallicity of quiescent galaxies at 0.60 ≤ $z$ ≤ 0.76 closely correlates with M/Re (a proxy for the gravitational potential or escape velocity), in that galaxies with deeper potential wells are more metal-rich. This supports the hypothesis that the relation arises due to the gravitational potential regulating the retention of metals by determining the escape velocity for metal-rich stellar and supernova ejecta to escape the system and avoid being recycled into later stellar generations. Conversely, we find no correlation between age and surface density ($M/R_\\mathrm{e}^2$) at 0.60 ≤ $z$ ≤ 0.76, despite this relation being strong at low redshift. We consider this change in the age–$M/R_\\mathrm{e}^2$ relation in the context of the redshift evolution of the star-forming and quiescent mass–size relations, and find our results are consistent with galaxies forming more compactly at higher redshifts and remaining compact throughout their evolution. Furthermore, galaxies appear to quench at a characteristic surface density that decreases with decreasing redshift. The $z$ ∼ 0 age–$M/R_\\mathrm{e}^2$ relation is therefore a result of building up the quiescent and star-forming populations with galaxies that formed at a range of redshifts and therefore a range of surface densities.
Publisher: EDP Sciences
Date: 20-01-2016
Publisher: American Astronomical Society
Date: 10-2022
Abstract: It is generally assumed that galaxies are a bimodal population in both star formation and structure star-forming galaxies are disks, while passive galaxies host large bulges or are entirely spheroidal. Here we test this scenario by presenting a full census of the kinematic morphologies of a volume-limited s le of galaxies in the local universe extracted from the MaNGA galaxy survey. We measure the integrated stellar line-of-sight velocity to velocity dispersion ratio ( V / σ ) for 4574 galaxies in the stellar mass range 9.75 log M ⋆ [ M ⊙ ] 11.75 . We show that at fixed stellar mass, the distribution of V / σ is not bimodal, and that a simple separation between fast and slow rotators is oversimplistic. Fast rotators are a mixture of at least two populations, referred to here as dynamically cold disks and intermediate systems, with disks dominating in both total stellar mass and number. When considering star-forming and passive galaxies separately, the star-forming population is almost entirely made up of disks, while the passive population is mixed, implying an array of quenching mechanisms. Passive disks represent ∼30% (both in number and mass) of passive galaxies, nearly a factor of two higher than that of slow rotators, reiterating that these are an important population for understanding galaxy quenching. These results paint a picture of a local universe dominated by disky galaxies, most of which become somewhat less rotation-supported upon or after quenching. While spheroids are present to a degree, they are certainly not the evolutionary end point for the majority of galaxies.
Publisher: American Astronomical Society
Date: 28-06-2022
Abstract: In this VERTICO early science paper we explore in detail how environmental mechanisms, identified in H i , affect the resolved properties of molecular gas reservoirs in cluster galaxies. The molecular gas is probed using ALMA ACA (+TP) observations of 12 CO(2–1) in 51 spiral galaxies in the Virgo cluster (of which 49 are detected), all of which are included in the VIVA H i survey. The s le spans a stellar mass range of 9 ≤ log M ⋆ / M ⊙ ≤ 11 . We study molecular gas radial profiles, isodensity radii, and surface densities as a function of galaxy H i deficiency and morphology. There is a weak correlation between global H i and H 2 deficiencies, and resolved properties of molecular gas correlate with H i deficiency: galaxies that have large H i deficiencies have relatively steep and truncated molecular gas radial profiles, which is due to the removal of low-surface-density molecular gas on the outskirts. Therefore, while the environmental mechanisms observed in H i also affect molecular gas reservoirs, there is only a moderate reduction of the total amount of molecular gas.
Publisher: Springer International Publishing
Date: 2022
Publisher: Oxford University Press (OUP)
Date: 02-2018
DOI: 10.1093/MNRAS/STY273
Publisher: Oxford University Press (OUP)
Date: 19-02-2019
DOI: 10.1093/MNRAS/STZ485
Publisher: Oxford University Press (OUP)
Date: 12-2021
Abstract: We present a detailed study of the stellar mass versus specific angular momentum (AM) relation (Fall relation) for a representative s le of 564 nearby galaxies in the eXtended GALEX Arecibo SDSS Survey (xGASS). We focus on the dependence of the Fall relation’s slope on galaxy type and the galaxy properties regulating its scatter. Stellar specific AM is determined by combining single-dish H i velocity widths and stellar mass profiles for all H i detections in the xGASS s le. At fixed morphology (or bulge-to-total ratio), we find that the power-law slope of the Fall relation is consistent with 2/3. However, when all galaxy types are combined, we recover a much shallower slope of ∼0.47. We show that this is a consequence of the change in galaxy morphology as a function of mass, highlighting that caution should be taken when using the slope of the Fall relation to constrain galaxy formation models without taking s le selection into account. We quantify the Fall relations scatter and show that H i gas fraction is the strongest correlated parameter for low stellar masses (Spearman correlation: ρs = 0.61), while the bulge-to-total ratio becomes slightly more dominant at higher masses (ρs = −0.29). Intriguingly, when only the disc components of galaxies are considered, H i gas fraction remains the strongest correlated parameter with the scatter of the relation (regardless of disc stellar mass). Our work provides one of the best characterizations of the Fall relation for a representative s le of galaxies in the local Universe.
Publisher: Oxford University Press (OUP)
Date: 20-05-2020
Abstract: We infer the intrinsic ionized gas kinematics for 383 star-forming galaxies across a range of integrated star formation rates (SFR ∈ [10−3, 102] M⊙ yr−1) at z ≲ 0.1 using a consistent 3D forward-modelling technique. The total s le is a combination of galaxies from the Sydney-AAO Multiobject Integral field Spectrograph (SAMI) Galaxy survey and DYnamics of Newly Assembled Massive Objects survey. For typical low-z galaxies taken from the SAMI Galaxy Survey, we find the vertical velocity dispersion (σv,z) to be positively correlated with measures of SFR, stellar mass, H i gas mass, and rotational velocity. The greatest correlation is with SFR surface density (ΣSFR). Using the total s le, we find σv,z increases slowly as a function of integrated SFR in the range SFR ∈ [10−3, 1] M⊙ yr−1 from 17 ± 3 to 24 ± 5 km s−1 followed by a steeper increase up to σv,z ∼80 km s−1 for SFR ≳ 1 M⊙ yr−1. This is consistent with recent theoretical models that suggest a σv,z floor driven by star formation feedback processes with an upturn in σv,z at higher SFR driven by gravitational transport of gas through the disc.
Publisher: EDP Sciences
Date: 20-01-2006
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2018
Publisher: Oxford University Press (OUP)
Date: 23-12-2019
Abstract: We present an analysis of the gas dynamics of star-forming galaxies at z ∼ 1.5 using data from the KMOS Galaxy Evolution Survey. We quantify the morphology of the galaxies using HSTcandels imaging parametrically and non-parametrically. We combine the H α dynamics from KMOS with the high-resolution imaging to derive the relation between stellar mass (M*) and stellar specific angular momentum (j*). We show that high-redshift star-forming galaxies at z ∼ 1.5 follow a power-law trend in specific stellar angular momentum with stellar mass similar to that of local late-type galaxies of the form j* ∝ M$_*^{0.53\\, \\pm \\, 0.10}$. The highest specific angular momentum galaxies are mostly disc-like, although generally both peculiar morphologies and disc-like systems are found across the sequence of specific angular momentum at a fixed stellar mass. We explore the scatter within the j* – M* plane and its correlation with both the integrated dynamical properties of a galaxy (e.g. velocity dispersion, Toomre Qg, H α star formation rate surface density ΣSFR) and its parametrized rest-frame UV / optical morphology (e.g. Sérsic index, bulge to total ratio, clumpiness, asymmetry, and concentration). We establish that the position in the j* – M* plane is strongly correlated with the star-formation surface density and the clumpiness of the stellar light distribution. Galaxies with peculiar rest-frame UV / optical morphologies have comparable specific angular momentum to disc- dominated galaxies of the same stellar mass, but are clumpier and have higher star formation rate surface densities. We propose that the peculiar morphologies in high-redshift systems are driven by higher star formation rate surface densities and higher gas fractions leading to a more clumpy interstellar medium.
Publisher: Oxford University Press (OUP)
Date: 05-2008
Publisher: AIP
Date: 2008
DOI: 10.1063/1.2973586
Publisher: Oxford University Press (OUP)
Date: 21-08-2023
Publisher: American Astronomical Society
Date: 17-11-2017
Publisher: American Astronomical Society
Date: 05-12-2012
Publisher: EDP Sciences
Date: 03-2020
DOI: 10.1051/0004-6361/201936556
Abstract: Context. This paper presents the analysis of optical integral field spectra for the H I eXtreme (H IX ) galaxy s le. H IX galaxies host at least 2.5 times more atomic gas (H I ) than expected from their optical R -band luminosity. Previous examination of their star formation activity and H I kinematics suggested that these galaxies stabilise their large H I discs (radii up to 94 kpc) against star formation due to their higher than average baryonic specific angular momentum. A comparison to semi-analytic models further showed that the elevated baryonic specific angular momentum is inherited from the high spin of the dark matter host. Aims. In this paper we now turn to the gas-phase metallicity as well as stellar and ionised gas kinematics in H IX galaxies to gain insights into recent accretion of metal-poor gas or recent mergers. Methods. We compare the stellar, ionised, and atomic gas kinematics, and examine the variation in the gas-phase metallicity throughout the stellar disc of H IX galaxies. Results. We find no indication for counter-rotation in any of the components, the central metallicities tend to be lower than average, but as low as expected for galaxies of similar H I mass. Metallicity gradients are comparable to other less H I -rich, local star forming galaxies. Conclusions. We conclude that H IX galaxies show no conclusive evidence for recent major accretion or merger events. Their overall lower metallicities are likely due to being hosted by high spin halos, which slows down their evolution and thus the enrichment of their interstellar medium.
Publisher: EDP Sciences
Date: 07-2023
DOI: 10.1051/0004-6361/202346599
Abstract: We analyse cold-gas distributions in Virgo cluster galaxies using resolved observations of CO(2-1), which traces molecular hydrogen (H 2 ), and H I from the Virgo Environment Traced In CO (VERTICO) and VLA Imaging of Virgo in Atomic Gas (VIVA) surveys. From a theoretical perspective, it is expected that environmental processes in clusters will have a stronger influence on diffuse atomic gas compared to the relatively dense molecular gas component, and that these environmental perturbations can compress the cold interstellar medium in cluster galaxies, leading to elevated star formation. In this work we observationally test these predictions for star-forming satellite galaxies within the Virgo cluster. We ided our Virgo galaxy s le into H I -normal, H I -tailed, and H I -truncated classes and show, unsurprisingly, that the H I -tailed galaxies have the largest quantitative H I asymmetries. We also compared Virgo galaxies to a control s le of non-cluster galaxies and find that the former, on average, have H I asymmetries that are 40 ± 10% larger than the latter. There is less separation between control, H I -normal, H I -tailed, and H I -truncated galaxies in terms of H 2 asymmetries, and on average, Virgo galaxies have H 2 asymmetries that are only marginally (20 ± 10%) larger than the control s le. We find a weak correlation between H I and H 2 asymmetries over our entire s le, but a stronger correlation for the galaxies that are strongly impacted by environmental perturbations. Finally, we ided the discs of the H I -tailed Virgo galaxies into a leading half and trailing half according to the observed tail direction. We find evidence for excess molecular gas mass on the leading halves of the disc. This excess molecular gas is accompanied by an excess in the star formation rate such that the depletion time is, on average, unchanged.
Publisher: Oxford University Press (OUP)
Date: 17-10-2018
Publisher: MDPI AG
Date: 31-10-2022
Abstract: Non-terrestrial networks (NTNs) have recently attracted elevated levels of interest in large-scale and ever-growing wireless communication networks through the utilization of flying objects, e.g., satellites and unmanned aerial vehicles/drones (UAVs). Interestingly, the applications of UAV-assisted networks are rapidly becoming an integral part of future communication services. This paper first overviews the key components of NTN while highlighting the significance of emerging UAV networks where for ex le, a group of UAVs can be used as nodes to exchange data packets and form a flying ad hoc network (FANET). In addition, both existing and emerging applications of the FANET are explored. Next, it provides key recent findings and the state-of-the-art of FANETs while examining various routing protocols based on cross-layer modeling. Moreover, a modeling perspective of FANETs is provided considering delay-tolerant networks (DTN) because of the intermittent nature of connectivity in low-density FANETs, where each node (or UAV) can perform store-carry-and-forward (SCF) operations. Indeed, we provide a case study of a UAV network as a DTN, referred to as DTN-assisted FANET. Furthermore, applications of machine learning (ML) in FANET are discussed. This paper ultimately foresees future research paths and problems for allowing FANET in forthcoming wireless communication networks.
Publisher: Oxford University Press (OUP)
Date: 09-11-2021
Abstract: We present the evolution of the star formation dispersion–stellar mass relation (σSFR–M⋆) in the DEVILS D10 region using new measurements derived using the ProSpect spectral energy distribution fitting code. We find that σSFR–M⋆ shows the characteristic ‘U-shape’ at intermediate stellar masses from 0.1 & z & 0.7 for a number of metrics, including using the deconvolved intrinsic dispersion. A physical interpretation of this relation is the combination of stochastic star formation and stellar feedback causing large scatter at low stellar masses and AGN feedback causing asymmetric scatter at high stellar masses. As such, the shape of this distribution and its evolution encodes detailed information about the astrophysical processes affecting star formation, feedback and the lifecycle of galaxies. We find that the stellar mass that the minimum σSFR occurs evolves linearly with redshift, moving to higher stellar masses with increasing lookback time and traces the turnover in the star-forming sequence. This minimum σSFR point is also found to occur at a fixed specific star formation rate (sSFR) at all epochs (sSFR ∼ 10−9.6 Gyr−1). The physical interpretation of this is that there exists a maximum sSFR at which galaxies can internally self-regulate on the tight sequence of star formation. At higher sSFRs, stochastic stellar processes begin to cause galaxies to be pushed both above and below the star-forming sequence leading to increased SFR dispersion. As the Universe evolves, a higher fraction of galaxies will drop below this sSFR threshold, causing the dispersion of the low stellar mass end of the star-forming sequence to decrease with time.
Publisher: American Astronomical Society
Date: 04-03-2019
Publisher: Oxford University Press (OUP)
Date: 12-08-2019
Abstract: The Galaxy And Mass Assembly (GAMA) survey has morphologically identified a class of ‘Little Blue Spheroid’ (LBS) galaxies whose relationship to other classes of galaxies we now examine in detail. Considering a s le of 868 LBSs, we find that such galaxies display similar but not identical colours, specific star formation rates, stellar population ages, mass-to-light ratios, and metallicities to Sd-Irr galaxies. We also find that LBSs typically occupy environments of even lower density than those of Sd-Irr galaxies, where ∼65 per cent of LBS galaxies live in isolation. Using deep, high-resolution imaging from VST KiDS and the new Bayesian, 2D galaxy profile modelling code profit, we further examine the detailed structure of LBSs and find that their Sérsic indices, sizes, and axial ratios are compatible with those of low-mass elliptical galaxies. We then examine SAMI Galaxy survey integral field emission line kinematics for a subset of 62 LBSs and find that the majority (42) of these galaxies display ordered rotation with the remainder displaying disturbed/non-ordered dynamics. Finally, we consider potential evolutionary scenarios for a population with this unusual combination of properties, concluding that LBSs are likely formed by a mixture of merger and accretion processes still recently active in low-redshift dwarf populations. We also infer that if LBS-like galaxies were subjected to quenching in a rich environment, they would plausibly resemble cluster dwarf ellipticals.
Publisher: Oxford University Press (OUP)
Date: 27-06-2020
Abstract: Observers experience a series of limitations when measuring galaxy kinematics, such as variable seeing conditions and aperture size. These effects can be reduced using empirical corrections, but these equations are usually applicable within a restrictive set of boundary conditions (e.g. Sérsic indices within a given range) that can lead to biases when trying to compare measurements made across a full kinematic survey. In this work, we present new corrections for two widely used kinematic parameters, λR and V/σ, that are applicable across a broad range of galaxy shapes, measurement radii, and ellipticities. We take a series of mock observations of N-body galaxy models and use these to quantify the relationship between the observed kinematic parameters, structural properties, and different seeing conditions. Derived corrections are then tested using the full catalogue of galaxies, including hydrodynamic models from the eagle simulation. Our correction is most effective for regularly rotating systems, yet the kinematic parameters of all galaxies – fast, slow, and irregularly rotating systems – are recovered successfully. We find that λR is more easily corrected than V/σ, with relative deviations of 0.02 and 0.06 dex, respectively. The relationship between λR and V/σ, as described by the parameter κ, also has a minor dependence on seeing conditions. These corrections will be particularly useful for stellar kinematic measurements in current and future integral field spectroscopic surveys of galaxies.
Publisher: Oxford University Press (OUP)
Date: 22-06-2017
Publisher: SAGE Publications
Date: 10-07-2016
Abstract: Background. A thorough understanding of the presence of different upper-limb somatosensory deficits poststroke and the relation with motor performance remains unclear. Additionally, knowledge about the relation between somatosensory deficits and visuospatial neglect is limited. Objective. To investigate the distribution of upper-limb somatosensory impairments and the association with unimanual and bimanual motor outcomes and visuospatial neglect. Methods. A cross-sectional observational study was conducted, including 122 patients within 6 months after stroke (median = 82 days interquartile range = 57-133 days). Somatosensory measurement included the Erasmus MC modification of the (revised) Nottingham Sensory Assessment (Em-NSA), Perceptual Threshold of Touch (PTT), thumb finding test, 2-point discrimination, and stereognosis subscale of the NSA. Upper-limb motor assessment comprised the Fugl-Meyer assessment, motricity index, Action Research Arm Test, and Adult-Assisting Hand Assessment Stroke. Screening for visuospatial neglect was performed using the Star Cancellation Test. Results. Upper-limb somatosensory impairments were common, with prevalence rates ranging from 21% to 54%. Low to moderate Spearman ρ correlations were found between somatosensory and motor deficits ( r = 0.22-0.61), with the strongest associations for PTT ( r = 0.56-0.61) and stereognosis ( r = 0.51-0.60). Visuospatial neglect was present in 27 patients (22%). Between-group analysis revealed somatosensory deficits that occurred significantly more often and more severely in patients with visuospatial neglect ( P .05). Results showed consistently stronger correlations between motor and somatosensory deficits in patients with visuospatial neglect ( r = 0.44-0.78) compared with patients without neglect ( r = 0.08-0.59). Conclusions. Somatosensory impairments are common in subacute patients poststroke and are related to motor outcome. Visuospatial neglect was associated with more severe upper-limb somatosensory impairments.
Publisher: EDP Sciences
Date: 02-2013
Publisher: Oxford University Press (OUP)
Date: 21-09-2020
Abstract: Photoelectric heating (PEH) influences the temperature and density of the interstellar medium (ISM), potentially also affecting star formation. PEH is expected to have a stronger effect on massive galaxies, as they host larger dust reservoirs compared to dwarf systems. Accordingly, in this paper, we study PEH effects in Milky Way-like galaxies using a smoothed particle hydrodynamics code, which self-consistently implements the evolution of the gas, dust, and interstellar radiation field. Dust evolution includes dust formation by stars, destruction by SNe, and growth in dense media. We find that PEH suppresses star formation due to the excess heating that reduces the ISM density. This suppression is seen across the entire range of gas fractions, star-formation recipes, dust models, and PEH efficiencies investigated by our code. The suppression ranges from negligible values to approximately a factor of five depending on the specific implementation. Galaxy models having higher gas fractions experience higher star-formation suppression. The adopted dust model also alters the extent of star-formation suppression. Moreover, when PEH is switched on, galaxy models show higher gas outflow rates and have higher loading factors, indicative of enhanced SNe feedback. In gas-rich models (i.e. a gas fraction of 0.5), we also find that PEH suppresses the formation of disc clumps via violent disc instabilities, and thus suppresses bulge formation via clump migration to the central regions.
Publisher: Oxford University Press (OUP)
Date: 12-10-2017
Publisher: Oxford University Press (OUP)
Date: 17-03-2020
Abstract: We use our catalogue of structural decomposition measurements for the extended GALEX Arecibo SDSS Survey (xGASS) to study the role of bulges both along and across the galaxy star-forming main sequence (SFMS). We show that the slope in the sSFR–M⋆ relation flattens by ∼0.1 dex per decade in M⋆ when re-normalizing specifice star formation rate (sSFR) by disc stellar mass instead of total stellar mass. However, recasting the sSFR–M⋆ relation into the framework of only disc-specific quantities shows that a residual trend remains against disc stellar mass with equivalent slope and comparable scatter to that of the total galaxy relation. This suggests that the residual declining slope of the SFMS is intrinsic to the disc components of galaxies. We further investigate the distribution of bulge-to-total ratios (B/T) as a function of distance from the SFMS (ΔSFRMS). At all stellar masses, the average B/T of local galaxies decreases monotonically with increasing ΔSFRMS. Contrary to previous works, we find that the upper envelope of the SFMS is not dominated by objects with a significant bulge component. This rules out a scenario in which, in the local Universe, objects with increased star formation activity are simultaneously experiencing a significant bulge growth. We suggest that much of the discrepancies between different works studying the role of bulges originate from differences in the methodology of structurally decomposing galaxies.
Publisher: EDP Sciences
Date: 21-03-2003
Publisher: SPIE
Date: 29-08-2022
DOI: 10.1117/12.2628142
Publisher: Elsevier BV
Date: 05-2023
Publisher: Oxford University Press (OUP)
Date: 12-09-2016
Publisher: Oxford University Press (OUP)
Date: 19-07-2021
Abstract: We present redshift-zero synthetic observational data considering dust attenuation and dust emission for the 30 galaxies of the Auriga project, calculated with the skirt radiative transfer code. The post-processing procedure includes components for star-forming regions, stellar sources, and diffuse dust taking into account stochastic heating of dust grains. This allows us to obtain realistic high-resolution broad-band images and fluxes from ultraviolet (UV) to submillimetre (submm) wavelengths. For the diffuse dust component, we consider two mechanisms for assigning dust to gas cells in the simulation. In one case, only the densest or the coldest gas cells are allowed to have dust, while in the other case this condition is relaxed to allow a larger number of dust-containing cells. The latter approach yields galaxies with a larger radial dust extent and an enhanced dust presence in the interspiral regions. At a global scale, we compare Auriga galaxies with observations by deriving dust scaling relations using spectral energy distribution fitting. At a resolved scale, we make a multiwavelength morphological comparison with nine well-resolved spiral galaxies from the DustPedia observational data base. We find that for both dust assignment methods, although the Auriga galaxies show a good overall agreement with observational dust properties, they exhibit a slightly higher specific dust mass. The multiwavelength morphological analysis reveals a good agreement between the Auriga and the observed galaxies in the optical wavelengths. In the mid- and far-infrared wavelengths, Auriga galaxies appear smaller and more centrally concentrated in comparison to their observed counterparts. We publicly release the multi-observer images and fluxes in 50 commonly used broad-band filters.
Publisher: MDPI AG
Date: 04-12-2021
DOI: 10.3390/S21238117
Abstract: Recent scientific and technological advancements driven by the Internet of Things (IoT), Machine Learning (ML) and Artificial Intelligence (AI), distributed computing and data communication technologies have opened up a vast range of opportunities in many scientific fields—spanning from fast, reliable and efficient data communication to large-scale cloud/edge computing and intelligent big data analytics. Technological innovations and developments in these areas have also enabled many opportunities in the space industry. The successful Mars landing of NASA’s Perseverance rover on 18 February 2021 represents another giant leap for humankind in space exploration. Emerging research and developments of connectivity and computing technologies in IoT for space/non-terrestrial environments is expected to yield significant benefits in the near future. This survey paper presents a broad overview of the area and provides a look-ahead of the opportunities made possible by IoT and space-based technologies. We first survey the current developments of IoT and space industry, and identify key challenges and opportunities in these areas. We then review the state-of-the-art and discuss future opportunities for IoT developments, deployment and integration to support future endeavors in space exploration.
Publisher: Oxford University Press (OUP)
Date: 07-01-2019
DOI: 10.1093/MNRAS/STZ019
Location: United Kingdom of Great Britain and Northern Ireland
Location: Italy
Start Date: 11-2022
End Date: 12-2023
Amount: $1,749,940.00
Funder: Australian Research Council
View Funded ActivityStart Date: 08-2021
End Date: 08-2024
Amount: $395,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2015
End Date: 09-2018
Amount: $325,500.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2019
End Date: 12-2021
Amount: $656,639.00
Funder: Australian Research Council
View Funded ActivityStart Date: 10-2018
End Date: 09-2023
Amount: $853,125.00
Funder: Australian Research Council
View Funded Activity