ORCID Profile
0000-0001-7542-2927
Current Organisation
Universität Hamburg
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Astronomical and Space Sciences | Cosmology and Extragalactic Astronomy
Publisher: Oxford University Press (OUP)
Date: 16-02-2011
Publisher: Oxford University Press (OUP)
Date: 22-02-2017
DOI: 10.1093/MNRAS/STX441
Publisher: Oxford University Press (OUP)
Date: 20-11-2017
Publisher: EDP Sciences
Date: 31-10-2012
Publisher: Oxford University Press (OUP)
Date: 06-04-2022
Abstract: We construct the halo mass function (HMF) from the GAMA (Galaxy And Mass Assembly) galaxy group catalogue over the mass range of 1012.7–1015.5 M⊙, and find good agreement with the expectation from Lambda cold dark matter. In comparison to previous studies, this result extends the mass range over which the HMF has now been measured over by an order of magnitude. We combine the GAMA data release (DR) 4 HMF with similar data from the Sloan Digital Sky Survey (SDSS) DR12 and REFLEX II (ROSAT-ESO Flux Limited X-ray Galaxy Cluster Survey) surveys, and fit a four-parameter Murray–Robotham–Power function, valid at $\\tilde{z} \\approx 0.1$, yielding a density normalization of log10 (ϕ* Mpc$^{3})= -3.96^{+0.55}_{-0.82}$, a high mass turnover of log10 (M* M$_{\\odot }^{-1})=14.13^{+0.43}_{-0.40}$, a low-mass power-law slope of $\\alpha =-1.68^{+0.21}_{-0.24}$, and a high-mass softening parameter of $\\beta =0.63^{+0.25}_{-0.11}$. If we fold in the constraint on ΩM from the Planck 2018 cosmology, we are able to reduce these uncertainties further, but this relies on the assumption that the power-law trend can be extrapolated from 1012.7 M⊙ to zero mass. Throughout, we highlight the effort needed to improve on our HMF measurement: improved halo mass estimates that do not rely on calibration to simulations reduced halo mass uncertainties needed to mitigate the strong Eddington bias that arises from the steepness of the HMF low-mass slope and deeper wider area spectroscopic surveys. To our halo mass limit of 1012.7 M⊙, we are directly resolving (‘seeing’) 41 ± 5 per cent of the total mass density, i.e. ΩM,& .7 = 0.128 ± 0.016, opening the door for the direct construction of three-dimensional dark matter mass maps at Mpc resolution.
Publisher: Oxford University Press (OUP)
Date: 20-07-2016
Publisher: Oxford University Press (OUP)
Date: 17-11-2017
Publisher: Oxford University Press (OUP)
Date: 18-11-2011
Publisher: Oxford University Press (OUP)
Date: 03-2013
DOI: 10.1093/MNRAS/STS717
Publisher: Oxford University Press (OUP)
Date: 11-06-2007
Publisher: Oxford University Press (OUP)
Date: 27-06-2011
Publisher: Oxford University Press (OUP)
Date: 14-04-2018
DOI: 10.1093/MNRAS/STY933
Publisher: Oxford University Press (OUP)
Date: 04-03-2014
Publisher: Oxford University Press (OUP)
Date: 11-12-2016
Publisher: Oxford University Press (OUP)
Date: 26-06-2014
Publisher: American Astronomical Society
Date: 07-03-2013
Publisher: Oxford University Press (OUP)
Date: 24-10-2011
Publisher: Oxford University Press (OUP)
Date: 03-2012
Publisher: Oxford University Press (OUP)
Date: 18-08-2022
Abstract: We derive single Sérsic fits and bulge-disc decompositions for 13 096 galaxies at redshifts z & 0.08 in the GAMA II equatorial survey regions in the Kilo-Degree Survey (KiDS) g, r, and i bands. The surface brightness fitting is performed using the Bayesian two-dimensional profile fitting code ProFit. We fit three models to each galaxy in each band independently with a fully automated Markov chain Monte Carlo analysis: a single Sérsic model, a Sérsic plus exponential and a point source plus exponential. After fitting the galaxies, we perform model selection and flag galaxies for which none of our models are appropriate (mainly mergers/Irregular galaxies). The fit quality is assessed by visual inspections, comparison to previous works, comparison of independent fits of galaxies in the overlap regions between KiDS tiles and bespoke simulations. The latter two are also used for a detailed investigation of systematic error sources. We find that our fit results are robust across various galaxy types and image qualities with minimal biases. Errors given by the MCMC underestimate the true errors typically by factors 2–3. Automated model selection criteria are accurate to $\\gt 90{{\\ \\rm per\\ cent}}$ as calibrated by visual inspection of a subs le of galaxies. We also present g−r component colours and the corresponding colour–magnitude diagram, consistent with previous works despite our increased fit flexibility. Such reliable structural parameters for the components of a erse s le of galaxies across multiple bands will be integral to various studies of galaxy properties and evolution. All results are integrated into the GAMA database.
Publisher: Oxford University Press (OUP)
Date: 13-01-2015
Publisher: Oxford University Press (OUP)
Date: 29-06-2013
DOI: 10.1093/MNRAS/STT890
Publisher: Oxford University Press (OUP)
Date: 19-12-2014
Publisher: Springer Berlin Heidelberg
Date: 2008
Publisher: Cambridge University Press (CUP)
Date: 07-2007
DOI: 10.1017/S1743921308017365
Abstract: The case is outlined for a new galaxy survey, including spectroscopy with AAOmega and sub-arcsecond multi-band imaging, that bridges a crucial gap between the SDSS and VVDS surveys. The science focus is to study structure and the relationship between matter and light on kpc-to-Mpc scales. The range of scales probed will enable direct constraints on the Cold Dark Matter model by: (1) measuring the halo mass function down to $10^{12}{\\cal M}_{\\odot}$ and its evolution to z ~ 0.4 (2) measuring the galaxy stellar mass function to very low mass limits of $10^{7}{\\cal M}_{\\odot}$ constraining baryonic feedback processes and (3) quantifying the environment-dependent merger rate since z ~ 0.4. Here, we highlight the fact that the high-resolution imaging will enable the bulge-disk decomposition of ~200000 galaxies in u – K , providing a valuable resource for statistical studies of bulge properties.
Publisher: Oxford University Press (OUP)
Date: 19-12-2015
Publisher: Oxford University Press (OUP)
Date: 10-2004
Publisher: Oxford University Press (OUP)
Date: 02-2010
Publisher: Oxford University Press (OUP)
Date: 24-11-2017
Publisher: Oxford University Press (OUP)
Date: 11-12-2009
Publisher: American Astronomical Society
Date: 16-04-2018
Publisher: Oxford University Press (OUP)
Date: 27-05-2013
DOI: 10.1093/MNRAS/STT770
Publisher: Oxford University Press (OUP)
Date: 12-2011
Publisher: American Astronomical Society
Date: 20-07-2020
Publisher: American Astronomical Society
Date: 10-06-2009
Publisher: Oxford University Press (OUP)
Date: 12-12-2011
Publisher: Oxford University Press (OUP)
Date: 03-08-2012
Publisher: American Astronomical Society
Date: 09-2007
DOI: 10.1086/520488
Publisher: Oxford University Press (OUP)
Date: 04-07-2011
Publisher: Oxford University Press (OUP)
Date: 30-07-2016
Publisher: Oxford University Press (OUP)
Date: 02-07-2013
Publisher: Oxford University Press (OUP)
Date: 13-10-2015
Publisher: American Astronomical Society
Date: 31-01-2014
Publisher: American Astronomical Society
Date: 14-02-2017
Publisher: EDP Sciences
Date: 07-2010
Publisher: American Astronomical Society
Date: 21-02-2007
DOI: 10.1086/513106
Publisher: Springer International Publishing
Date: 2016
Publisher: Oxford University Press (OUP)
Date: 04-09-2013
Publisher: Oxford University Press (OUP)
Date: 10-2009
Publisher: Oxford University Press (OUP)
Date: 05-2008
Publisher: Oxford University Press (OUP)
Date: 03-12-2015
Publisher: American Association for the Advancement of Science (AAAS)
Date: 24-04-2020
Abstract: Fine-structure constant measurements 13 Ga ago, plus lower redshift data, test space-time variation of a fundamental constant.
Publisher: Cambridge University Press (CUP)
Date: 09-2011
DOI: 10.1017/S1743921312009404
Abstract: Present and past gas-fuelling of galaxies is expected to depend upon both the properties of the galaxies themselves, as well as their larger-scale environments. In the case of galaxies in groups the environment, i.e the group mass, can be probed by measuring the velocity dispersion of the group members, as done with the GAMA Galaxy Group catalogue (Robotham et al . 2011), probing the halo mass function all the way to small groups. The gas-fuelling rate of normal late-type galaxies can be traced by the SFR under the assumption of a steady state between gas-fuelling and gas-consumption by SF. We present a method to estimate disk opacities from UV/optical photometric characteristics, calibrated using the radiative transfer model of Popescu et al . (2011), applied to UV-Opt-FIR GAMA/H-ATLAS photometry for a subset of GAMA galaxies. We use the method to extract attenuation corrected SFRs for a large s le of late-type GAMA galaxies, which we use in an initial application to constrain the dependency of star formation/gas-fuelling in late-type galaxies on mass of parent DMH, and compactness of galaxy group.
Publisher: Oxford University Press (OUP)
Date: 11-08-2011
Publisher: Cambridge University Press (CUP)
Date: 06-2008
DOI: 10.1017/S1743921308027981
Abstract: The GAMA survey aims to deliver 250,000 optical spectra (3–7 Å resolution) over 250 sq. degrees to spectroscopic limits of r AB 19.8 and K AB 17.0 mag. Complementary imaging will be provided by GALEX, VST, UKIRT, VISTA, HERSCHEL and ASKAP to comparable flux levels leading to a definitive multi-wavelength galaxy database. The data will be used to study all aspects of cosmic structures on 1kpc to 1Mpc scales spanning all environments and out to a redshift limit of z ≈ 0.4. Key science drivers include the measurement of: the halo mass function via group velocity dispersions the stellar, HI, and baryonic mass functions galaxy component mass-size relations the recent merger and star-formation rates by mass, types and environment. Detailed modeling of the spectra, broad SEDs, and spatial distributions should provide in idual star formation histories, ages, bulge-disc decompositions and stellar bulge, stellar disc, dust disc, neutral HI gas and total dynamical masses for a significant subset of the s le (~ 100k) spanning both the giant and dwarf galaxy populations. The survey commenced March 2008 with 50k spectra obtained in 21 clear nights using the Anglo Australian Observatory's new multi-fibre-fed bench-mounted dual-beam spectroscopic system (AAΩ).
Publisher: Oxford University Press (OUP)
Date: 12-2010
Publisher: EDP Sciences
Date: 28-04-2016
Publisher: Oxford University Press (OUP)
Date: 11-12-2017
Publisher: Oxford University Press (OUP)
Date: 22-10-2012
Publisher: Oxford University Press (OUP)
Date: 22-01-2018
DOI: 10.1093/MNRAS/STY124
Publisher: EDP Sciences
Date: 07-2010
Publisher: Oxford University Press (OUP)
Date: 18-09-2014
Publisher: Oxford University Press (OUP)
Date: 11-12-2017
Publisher: Oxford University Press (OUP)
Date: 02-03-2011
Publisher: Oxford University Press (OUP)
Date: 20-05-2014
DOI: 10.1093/MNRAS/STU727
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201731606
Abstract: Context. In the currently debated context of using clusters of galaxies as cosmological probes, the need for well-defined cluster s les is critical. Aims. The XXL Survey has been specifically designed to provide a well characterised s le of some 500 X-ray detected clusters suitable for cosmological studies. The main goal of present article is to make public and describe the properties of the cluster catalogue in its present state, as well as of associated catalogues of more specific objects such as super-clusters and fossil groups. Methods. Following from the publication of the hundred brightest XXL clusters, we now release a s le containing 365 clusters in total, down to a flux of a few 10 −15 erg s −1 cm −2 in the [0.5–2] keV band and in a 1′ aperture. This release contains the complete subset of clusters for which the selection function is well determined plus all X-ray clusters which are, to date, spectroscopically confirmed. In this paper, we give the details of the follow-up observations and explain the procedure adopted to validate the cluster spectroscopic redshifts. Considering the whole XXL cluster s le, we have provided two types of selection, both complete in a particular sense: one based on flux-morphology criteria, and an alternative based on the [0.5–2] keV flux within 1 arcmin of the cluster centre. We have also provided X-ray temperature measurements for 80% of the clusters having a flux larger than 9 × 10 −15 erg s −1 cm −2 . Results. Our cluster s le extends from z ~ 0 to z ~ 1.2, with one cluster at z ~ 2. Clusters were identified through a mean number of six spectroscopically confirmed cluster members. The largest number of confirmed spectroscopic members in a cluster is 41. Our updated luminosity function and luminosity–temperature relation are compatible with our previous determinations based on the 100 brightest clusters, but show smaller uncertainties. We also present an enlarged list of super-clusters and a s le of 18 possible fossil groups. Conclusions. This intermediate publication is the last before the final release of the complete XXL cluster catalogue when the ongoing C2 cluster spectroscopic follow-up is complete. It provides a unique inventory of medium-mass clusters over a 50 deg 2 area out to z ~ 1.
Publisher: Oxford University Press (OUP)
Date: 11-05-2013
Publisher: Oxford University Press (OUP)
Date: 08-11-2010
Publisher: Oxford University Press (OUP)
Date: 22-03-2018
DOI: 10.1093/MNRAS/STY769
Publisher: Oxford University Press (OUP)
Date: 12-04-2016
DOI: 10.1093/MNRAS/STW747
Publisher: Oxford University Press (OUP)
Date: 09-09-2015
Publisher: Oxford University Press (OUP)
Date: 03-2010
Publisher: Oxford University Press (OUP)
Date: 05-03-2012
Publisher: American Astronomical Society
Date: 08-08-2019
Publisher: EDP Sciences
Date: 10-2022
DOI: 10.1051/0004-6361/202243101
Abstract: Aims. The circumgalactic medium (CGM) plays an important role in galaxy evolution as the main interface between the star-forming body of galaxies and the surrounding cosmic network of in- and out-flowing matter. In this work, we aim to characterize the hot phase of the CGM in a large s le of galaxies using recent soft-X-ray observations made by SRG /eROSITA. Methods. We stack X-ray events from the ‘eROSITA Final Equatorial Depth Survey’ (eFEDS) around central galaxies in the 9hr field of the ‘GAlaxy and Mass Assembly’ (GAMA) survey to construct radially projected X-ray luminosity profiles in the 0.5–2 keV rest frame energy band as a function of their stellar mass and specific star formation rate. We consider s les of quiescent (star-forming) galaxies in the stellar mass range 2 × 10 10 –10 12 M ⊙ (3 × 10 9 –6 × 10 11 M ⊙ ). Results. For quiescent galaxies, the X-ray profiles are clearly extended throughout the available mass range however, the measured profile is likely biased high because of projection effects, as these galaxies tend to live in dense and hot environments. For the most massive star-forming s les (≥10 11 M ⊙ ), there is a hint of detection of extended emission. On the other hand, for star-forming galaxies with 10 11 M ⊙ the X-ray stacked profiles are compatible with unresolved sources and are consistent with the expected emission from faint active galactic nuclei (AGN) and X-ray binaries. We measure for the first time the mean relation between average X-ray luminosity and stellar mass separately for quiescent and star-forming galaxies. We find that the relation is different for the two galaxy populations: high-mass (≥10 11 M ⊙ ) star-forming or quiescent galaxies follow the expected scaling of virialized hot haloes, while lower mass star-forming galaxies show a less prominent luminosity and a weaker dependence on stellar mass consistent with empirical models of the population of weak AGN. When comparing our results with state-of-the-art numerical simulations (IllustrisTNG and EAGLE), we find overall consistency on the average emission on large ( 80 kpc) scales at masses ≥10 11 M ⊙ , but disagreement on the small scales, where brighter-than-observed compact cores are predicted. The simulations also do not predict the clear differentiation that we observe between quiescent and star-forming galaxies in our s les. Conclusions. This is a stepping stone towards a more profound understanding of the hot phase of the CGM, which holds a key role in the regulation of star formation. Future analysis using eROSITA all-sky survey data, combined with future generation galaxy evolution surveys, shall provide much enhanced quantitative measurements and mapping of the CGM and its hot phase(s).
Publisher: Oxford University Press (OUP)
Date: 06-06-2012
Publisher: EDP Sciences
Date: 09-2021
DOI: 10.1051/0004-6361/202140500
Abstract: Context. Galaxies are biased tracers of the underlying network of dark matter. The strength of this bias depends on various galaxy properties and on redshift. One of the methods used to study these dependences of the bias is measurement of galaxy clustering. Such studies are made using galaxy s les from various catalogues, which frequently bear their own problems related to s le selection methods. It is therefore crucial to understand how s le choice influences clustering measurements and which galaxy property is the most direct tracer of the galaxy environment. Aims. We investigate how different galaxy properties, such as luminosities in the u , g , r , J , and K bands, stellar mass, star formation rate, and specific star formation rate, trace the environment in the local universe. We also study the effect of survey flux limits on galaxy clustering measurements. Methods. We measure the two-point correlation function and marked correlation functions using the aforementioned properties as marks. We use a nearly stellar-mass-complete galaxy s le in the redshift range 0.1 z 0.16 from the Galaxy and Mass Assembly (GAMA) survey with a flux limit of r 19.8. Further, we impose a brighter flux limit of r 17.8 on our s le and repeated the measurements to study how this affects galaxy clustering analysis. We compare our results to measurements from the Sloan Digital Sky Survey with flux limits of r 17.8 and r 16.8. Results. We show that the stellar mass is the most direct tracer of galaxy environment, the K -band luminosity being a good substitute, although such a proxy s le misses close pairs of evolved, red galaxies. We also show that the u -band luminosity can be a proxy to the star formation rate in the context of galaxy clustering. We observe an effect of the survey flux limit on clustering studies s les with a higher flux limit (smaller magnitude) miss some information about close pairs of starburst galaxies.
Publisher: Oxford University Press (OUP)
Date: 09-07-2013
Publisher: Oxford University Press (OUP)
Date: 22-10-2013
Publisher: European Southern Observatory (ESO)
Date: 2019
Publisher: American Astronomical Society
Date: 10-2005
DOI: 10.1086/433169
Publisher: Oxford University Press (OUP)
Date: 03-2011
Publisher: Oxford University Press (OUP)
Date: 12-04-2016
DOI: 10.1093/MNRAS/STW832
Publisher: Oxford University Press (OUP)
Date: 30-12-2015
Publisher: Oxford University Press (OUP)
Date: 20-11-2015
Publisher: Oxford University Press (OUP)
Date: 05-10-2018
Publisher: Oxford University Press (OUP)
Date: 24-08-2015
Publisher: Oxford University Press (OUP)
Date: 24-01-2013
DOI: 10.1093/MNRAS/STS633
Publisher: Oxford University Press (OUP)
Date: 07-01-2013
DOI: 10.1093/MNRAS/STS510
Publisher: Oxford University Press (OUP)
Date: 04-2004
Publisher: Oxford University Press (OUP)
Date: 05-2006
Publisher: Oxford University Press (OUP)
Date: 06-07-2016
Publisher: Oxford University Press (OUP)
Date: 21-12-2012
Publisher: American Astronomical Society
Date: 22-04-2008
DOI: 10.1086/588582
Publisher: Oxford University Press (OUP)
Date: 11-08-2007
Publisher: Cambridge University Press (CUP)
Date: 08-2006
DOI: 10.1017/S1743921306004960
Abstract: Galaxy bimodality is caused by the bulge-disc nature of galaxies as opposed to two distinct galaxy classes. This is evident in the colour-structure plane which clearly shows that elliptical galaxies (bulge-only) lie in the red compact peak and late-type spiral galaxies (disc-dominated) lie in the blue diffuse peak. Early-type spirals (bulge plus disc systems) sprawl across both peaks. However after bulge-disc decomposition the bulges of early-type spirals lie exclusively in the red compact peak and their discs in the blue diffuse peak (exceptions exist but are rare, e.g., dust reddened edge-on discs and blue pseudo-bulges). Movement between these two peaks is not trivial because whilst switching off star-formation can transform colours from blue to red, modifying the orbits of ~1 billion stars from a planar diffuse structure to a triaxial compact structure is problematic (essentially requiring an equal mass merger). We propose that the most plausible explanation for the dual structure of galaxies is that galaxy formation proceeds in two stages. First an initial collapse phase (forming a centrally concentrated core and black hole), followed by splashback, infall and accretion (forming a planar rotating disc). Dwarf systems coule perhaps follow the same scenario but the lack of low luminosity bulge-disc systems would imply that the two components must rapidly blend to form a single flattened spheroidal system.
Publisher: Oxford University Press (OUP)
Date: 11-07-2016
Publisher: Oxford University Press (OUP)
Date: 07-06-2006
Publisher: Cambridge University Press (CUP)
Date: 11-2005
Publisher: European Southern Observatory (ESO)
Date: 2019
Publisher: Oxford University Press (OUP)
Date: 26-11-2014
Publisher: European Southern Observatory (ESO)
Date: 2019
Publisher: Oxford University Press (OUP)
Date: 15-05-2017
Publisher: Oxford University Press (OUP)
Date: 29-08-2014
Publisher: EDP Sciences
Date: 11-2018
DOI: 10.1051/0004-6361/201833785
Abstract: Context . Massive ultra-compact galaxies (MUGs) are common at z = 2−3, but very rare in the nearby Universe. Simulations predict that the few surviving MUGs should reside in galaxy clusters, whose large relative velocities prevent them from merging, thus maintaining their original properties (namely stellar populations, masses, sizes and dynamical state). Aims. Our goal is to obtain a complete census of the MUG population at 0.02 z 0.3, determining the number density, population properties and environment. Methods . We have taken advantage of the high-completeness, large-area spectroscopic GAMA survey, complementing it with deeper imaging from the KiDS and VIKING surveys. We find a set of 22 bona-fide MUGs, defined as having high stellar mass ( 8 × 10 10 M ⊙ ) and compact size ( R e 2 kpc). An additional set of seven lower-mass objects (6 × 10 10 M ⋆ / M ⊙ 8 × 10 10 ) are also potential candidates according to typical mass uncertainties. Results . The comoving number density of MUGs at low redshift ( z 0.3) is constrained at (1.0 ± 0.4)×10 −6 Mpc −3 , consistent with galaxy evolution models. However, we find a mixed distribution of old and young galaxies, with a quarter of the s le representing (old) relics. MUGs have a predominantly early or swollen disk morphology (Sérsic index 1 n 2.5) with high stellar surface densities (⟨Σ e ⟩∼10 10 M ⊙ Kpc −2 ). Interestingly, a large fraction feature close companions – at least in projection – suggesting that many (but not all) reside in the central regions of groups. Halo masses show these galaxies inhabit average-mass groups. Conclusions . As MUGs are found to be almost equally distributed among environments of different masses, their relative fraction is higher in more massive overdensities, matching the expectations that some of these galaxies fell in these regions at early times. However, there must be another channel leading some of these galaxies to an abnormally low merger history because our s le shows a number of objects that do not inhabit particularly dense environments.
Publisher: Oxford University Press (OUP)
Date: 02-07-2013
DOI: 10.1093/MNRAS/STT855
Publisher: Oxford University Press (OUP)
Date: 10-10-2005
Publisher: EDP Sciences
Date: 10-2018
DOI: 10.1051/0004-6361/201832697
Abstract: Aims : We aim to investigate if the environment (characterised by the host dark matter halo mass) plays any role in shaping the galaxy star formation main sequence (MS). Methods : The Galaxy and Mass Assembly project (GAMA) combines a spectroscopic survey with photometric information in 21 bands from the far-ultraviolet (FUV) to the far-infrared (FIR). Stellar masses and dust-corrected star-formation rates (SFR) are derived from spectral energy distribution (SED) modelling using MAGPHYS. We use the GAMA galaxy group catalogue to examine the variation of the fraction of star-forming galaxies (SFG) and properties of the MS with respect to the environment. Results : We examine the environmental dependence for stellar mass selected s les without preselecting star-forming galaxies and study any dependence on the host halo mass separately for centrals and satellites out to z ∼ 0.3. We find the SFR distribution at fixed stellar mass can be described by the combination of two Gaussians (referred to as the star-forming Gaussian and the quiescent Gaussian). Using the observed bimodality to define SFG, we investigate how the fraction of SFG F(SFG) and properties of the MS change with environment. For centrals, the position of the MS is similar to the field but with a larger scatter. No significant dependence on halo mass is observed. For satellites, the position of the MS is almost always lower (by ∼0.2 dex) compared to the field and the width is almost always larger. F(SFG) is similar between centrals (in different halo mass bins) and field galaxies. However, for satellites F(SFG) decreases with increasing halo mass and this dependence is stronger towards lower redshift.
Publisher: Oxford University Press (OUP)
Date: 10-05-2012
Publisher: EDP Sciences
Date: 15-06-2016
Publisher: Oxford University Press (OUP)
Date: 26-07-2011
Publisher: Oxford University Press (OUP)
Date: 08-2006
Publisher: Oxford University Press (OUP)
Date: 13-03-2015
DOI: 10.1093/MNRAS/STV237
Publisher: Oxford University Press (OUP)
Date: 09-2003
Publisher: Oxford University Press (OUP)
Date: 07-06-2016
Publisher: Oxford University Press (OUP)
Date: 02-2012
Publisher: Oxford University Press (OUP)
Date: 06-2005
Publisher: Oxford University Press (OUP)
Date: 30-07-2016
Publisher: Oxford University Press (OUP)
Date: 14-01-2023
Abstract: Despite the success of galaxy-scale strong gravitational lens studies with Hubble-quality imaging, a number of well-studied strong lenses remains small. As a result, robust comparisons of the lens models to theoretical predictions are difficult. This motivates our application of automated Bayesian lens modelling methods to observations from public data releases of overlapping large ground-based imaging and spectroscopic surveys: Kilo-Degree Survey (KiDS) and Galaxy and Mass Assembly (GAMA), respectively. We use the open-source lens modelling software pyautolens to perform our analysis. We demonstrate the feasibility of strong lens modelling with large-survey data at lower resolution as a complementary avenue to studies that utilize more time-consuming and expensive observations of in idual lenses at higher resolution. We discuss advantages and challenges, with special consideration given to determining background source redshifts from single-aperture spectra and to disentangling foreground lens and background source light. High uncertainties in the best-fitting parameters for the models due to the limits of optical resolution in ground-based observatories and the small s le size can be improved with future study. We give broadly applicable recommendations for future efforts, and with proper application, this approach could yield measurements in the quantities needed for robust statistical inference.
Publisher: EDP Sciences
Date: 20-11-2018
DOI: 10.1051/0004-6361/201731880
Abstract: We present the version of the point source catalogue of the XXL Survey that was used, in part, in the first series of XXL papers. In this paper we release, in our database in Milan and at CDS: (i) the X-ray source catalogue with 26 056 objects in two areas of 25 deg 2 with a flux limit (at 3 σ ) of ~10 −15 erg s −1 cm −2 in [0.5–2] keV, and ~ 3 × 10 −15 erg s −1 cm −2 in [2–10] keV, yielding a 90% completeness limit of 5.8 × 10 −15 and 3.8 × 10 −14 respectively (ii) the associated multiwavelength catalogues with candidate counterparts of the X-ray sources in the infrared, near-infrared, optical, and ultraviolet (plus spectroscopic redshift when available) and (iii) a catalogue of spectroscopic redshifts recently obtained in the southern XXL area. We also present the basic properties of the X-ray point sources and their counterparts. Other catalogues described in the second series of XXL papers will be released contextually, and will constitute the second XXLdata release.
Publisher: Oxford University Press (OUP)
Date: 02-2004
Publisher: Oxford University Press (OUP)
Date: 03-11-2022
Abstract: Galaxies fall broadly into two categories: star-forming (blue) galaxies and quiescent (red) galaxies. In between, one finds the less populated ‘green valley’. Some of these galaxies are suspected to be in the process of ceasing their star formation through a gradual exhaustion of gas supply, or already dead and experiencing a rejuvenation of star formation through fuel injection. We use the Galaxy And Mass Assembly (GAMA) database and the Galaxy Zoo citizen science morphological estimates to compare the morphology of galaxies in the green valley with those in the red sequence and blue cloud. Our goal is to examine the structural differences within galaxies that fall in the green valley, and what brings them there. Previous results found that disc features such as rings and lenses are more prominently represented in the green-valley population. We revisit this with a similar sized data set of galaxies with morphology labels provided by the Galaxy Zoo for the GAMA fields based on new Kilo-Degree Survey (KiDS) images. Our aim is to compare the results from expert classification qualitatively with those of citizen science. We observe that ring structures are indeed found more commonly in green-valley galaxies compared with their red and blue counterparts. We suggest that ring structures are a consequence of disc galaxies in the green valley actively exhibiting the characteristics of fading discs and evolving disc morphology of galaxies. We note that the progression from blue to red correlates with loosening spiral-arm structure.
Publisher: Oxford University Press (OUP)
Date: 19-06-2015
Publisher: Oxford University Press (OUP)
Date: 14-12-2013
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: SPIE
Date: 09-08-2016
DOI: 10.1117/12.2232832
Publisher: Oxford University Press (OUP)
Date: 22-03-2014
DOI: 10.1093/MNRAS/STU354
Publisher: Cambridge University Press (CUP)
Date: 2010
DOI: 10.1071/AS09053
Abstract: A heuristic greedy algorithm is developed for efficiently tiling spatially dense redshift surveys. In its first application to the Galaxy and MassAssembly (GAMA) redshift survey we find it rapidly improves the spatial uniformity of our data, and naturally corrects for any spatial bias introduced by the 2dF multi-object spectrograph. We make conservative predictions for the final state of the GAMA redshift survey after our final allocation of time, and can be confident that even if worse than typical weather affects our observations, all of our main survey requirements will be met.
Publisher: Oxford University Press (OUP)
Date: 05-06-2018
Abstract: We present the dust mass function (DMF) of 15 750 galaxies with redshift $z$ & 0.1, drawn from the overlapping area of the GAMA and H-ATLAS surveys. The DMF is derived using the density corrected Vmax method, where we estimate Vmax using: (i) the normal photometric selection limit (pVmax) and (ii) a bivariate brightness distribution (BBD) technique, which accounts for two selection effects. We fit the data with a Schechter function, and find $M^{*}=(4.65 \\pm 0.18)\\times 10^{7}\\,h^2_{70}\\, \\mathrm{ M}_{\\odot }$, α = (−1.22 ± 0.01), $\\phi ^{*}=(6.26 \\pm 0.28)\\times 10^{-3}\\,h^3_{70}\\,\\rm Mpc^{-3}\\,dex^{-1}$. The resulting dust mass density parameter integrated down to 104 M⊙ is Ωd = (1.11 ± 0.02) × 10−6 which implies the mass fraction of baryons in dust is $f_{m_\\mathrm{ b}}=(2.40\\pm 0.04)\\times 10^{-5}$ cosmic variance adds an extra 7–17 per cent uncertainty to the quoted statistical errors. Our measurements have fewer galaxies with high dust mass than predicted by semi-analytic models. This is because the models include too much dust in high stellar mass galaxies. Conversely, our measurements find more galaxies with high dust mass than predicted by hydrodynamical cosmological simulations. This is likely to be from the long time-scales for grain growth assumed in the models. We calculate DMFs split by galaxy type and find dust mass densities of Ωd = (0.88 ± 0.03) × 10−6 and Ωd = (0.060 ± 0.005) × 10−6 for late types and early types, respectively. Comparing to the equivalent galaxy stellar mass functions (GSMF) we find that the DMF for late types is well matched by the GSMF scaled by (8.07 ± 0.35) × 10−4.
Publisher: Oxford University Press (OUP)
Date: 08-05-2014
DOI: 10.1093/MNRAS/STU632
Publisher: Oxford University Press (OUP)
Date: 19-11-2014
Publisher: Oxford University Press (OUP)
Date: 20-11-2015
Publisher: Cambridge University Press (CUP)
Date: 2019
DOI: 10.1017/PASA.2019.16
Abstract: We have observed the G23 field of the Galaxy AndMass Assembly (GAMA) survey using the Australian Square Kilometre Array Pathfinder (ASKAP) in its commissioning phase to validate the performance of the telescope and to characterise the detected galaxy populations. This observation covers ~48 deg 2 with synthesised beam of 32.7 arcsec by 17.8 arcsec at 936MHz, and ~39 deg 2 with synthesised beam of 15.8 arcsec by 12.0 arcsec at 1320MHz. At both frequencies, the root-mean-square (r.m.s.) noise is ~0.1 mJy/beam. We combine these radio observations with the GAMA galaxy data, which includes spectroscopy of galaxies that are i-band selected with a magnitude limit of 19.2. Wide-field Infrared Survey Explorer (WISE) infrared (IR) photometry is used to determine which galaxies host an active galactic nucleus (AGN). In properties including source counts, mass distributions, and IR versus radio luminosity relation, the ASKAP-detected radio sources behave as expected. Radio galaxies have higher stellar mass and luminosity in IR, optical, and UV than other galaxies. We apply optical and IR AGN diagnostics and find that they disagree for ~30% of the galaxies in our s le. We suggest possible causes for the disagreement. Some cases can be explained by optical extinction of the AGN, but for more than half of the cases we do not find a clear explanation. Radio sources aremore likely (~6%) to have an AGN than radio quiet galaxies (~1%), but the majority of AGN are not detected in radio at this sensitivity.
Publisher: Oxford University Press (OUP)
Date: 23-02-2018
DOI: 10.1093/MNRAS/STY440
Publisher: Oxford University Press (OUP)
Date: 07-02-2013
DOI: 10.1093/MNRAS/STT030
Publisher: Springer Netherlands
Date: 2007
Publisher: Oxford University Press (OUP)
Date: 12-02-2014
Publisher: Springer Netherlands
Date: 2007
Publisher: Oxford University Press (OUP)
Date: 07-05-2012
Publisher: Oxford University Press (OUP)
Date: 08-03-2013
DOI: 10.1093/MNRAS/STT156
Publisher: Oxford University Press (OUP)
Date: 20-03-0031
DOI: 10.1093/MNRAS/STT310
Publisher: Oxford University Press (OUP)
Date: 16-03-2018
DOI: 10.1093/MNRAS/STY688
Publisher: American Astronomical Society
Date: 11-07-2013
Start Date: 2018
End Date: 11-2022
Amount: $390,877.00
Funder: Australian Research Council
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