ORCID Profile
0000-0002-4003-0904
Current Organisation
University of Western Australia
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Astronomical and Space Sciences | Cosmology and Extragalactic Astronomy | Galactic Astronomy | Astronomical and Space Instrumentation | Photonics, Optoelectronics and Optical Communications |
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Physical Sciences | Expanding Knowledge in Technology | Expanding Knowledge in Engineering | Scientific Instruments | Electronic Information Storage and Retrieval Services
Related Links
Publications
Arsenic(V) biosorption by charred orange peel in aqueous environments
Publisher: Informa UK Limited
Date: 09-11-2016
DOI: 10.1080/15226514.2015.1109604
Abstract: Biosorption efficiency of natural orange peel (NOP) and charred orange peel (COP) was examined for the immobilization of arsenate (As(V)) in aqueous environments using batch sorption experiments. Sorption experiments were carried out as a function of pH, time, initial As(V) concentration and biosorbent dose, using NOP and COP (pretreated with sulfuric acid). Arsenate sorption was found to be maximum at pH 6.5, with higher As(V) removal percentage (98%) by COP than NOP (68%) at 4 g L(-1) optimum biosorbent dose. Sorption isotherm data exhibited a higher As(V) sorption (60.9 mg g(-1)) for COP than NOP (32.7 mg g(-1)). Langmuir model provided the best fit to describe As(V) sorption. Fourier transform infrared spectroscopy and scanning electron microscopy combined with energy dispersive X-ray spectroscopy analyses revealed that the -OH, -COOH, and -N-H surface functional groups were involved in As(V) biosorption and the meso- to micro-porous structure of COP sequestered significantly (2-times) higher As(V) than NOP, respectively. Arsenate desorption from COP was found to be lower (10%) than NOP (26%) up to the third regeneration cycle. The results highlight that this method has a great potential to produce unique 'charred' materials from the widely available biowastes, with enhanced As(V) sorption properties.
Primordial globular clusters, X-ray binaries and cosmological reionization
Publisher: Oxford University Press (OUP)
Date: 11-05-2009
Galaxy and Mass Assembly (GAMA): formation and growth of elliptical galaxies in the group environment
Publisher: Oxford University Press (OUP)
Date: 22-02-2017
DOI: 10.1093/MNRAS/STX441
Galaxy Groups: Proceedings from a Swinburne University Workshop
Publisher: Cambridge University Press (CUP)
Date: 2005
DOI: 10.1071/AS05030
Abstract: We present the proceedings from a two-day workshop held at Swinburne University on 2005 May 24–25. The workshop participants highlighted current Australian research on both theoretical and observational aspects of galaxy groups. These proceedings include short one-page summaries of a number of the talks presented at the workshop. The talks presented ranged from reconciling N -body simulations with observations, to the Hı content of galaxies in groups and the existence of ‘dark galaxies’. The formation and existence of ultra-compact dwarfs in groups, and a new supergroup in Eridanus were also discussed.
The hierarchical structure of galactic haloes
Publisher: Oxford University Press (OUP)
Date: 18-12-2021
Abstract: We build upon Ordering Points To Identify the Clustering Structure (optics ), a hierarchical clustering algorithm well known to be a robust data miner, in order to produce halo-optics , an algorithm designed for the automatic detection and extraction of all meaningful clusters between any two arbitrary sizes. We then apply halo-optics to the 3D spatial positions of halo particles within four separate synthetic Milky Way-type galaxies, classifying the stellar and dark matter structural hierarchies. Through visualization of the halo-optics output, we compare its structure identification to the state-of-the-art galaxy/(sub)halo finder VELOCIraptor , finding excellent agreement even though halo-optics does not consider kinematic information in this current implementation. We conclude that halo-optics is a robust hierarchical halo finder, although its determination of lower spatial-density features such as the tails of streams could be improved with the inclusion of extra localized information such as particle kinematics and stellar metallicity into its distance metric.
Quenching time-scales of galaxies in the eagle simulations
Publisher: Oxford University Press (OUP)
Date: 29-05-2019
The distribution and properties of DLAs at z ≤ 2 in the EAGLE simulations
Publisher: Oxford University Press (OUP)
Date: 18-12-2021
Abstract: Determining the spatial distribution and intrinsic physical properties of neutral hydrogen on cosmological scales is one of the key goals of next-generation radio surveys. We use the EAGLE galaxy formation simulations to assess the properties of d ed Lyman α absorbers (DLAs) that are associated with galaxies and their underlying dark matter haloes between 0 ≤ z ≤ 2. We find that the covering fraction of DLAs increases at higher redshift a significant fraction of neutral atomic hydrogen (H i) resides in the outskirts of galaxies with stellar mass ≥1010 M⊙ and the covering fraction of DLAs in the circumgalactic medium (CGM) is enhanced relative to that of the interstellar medium (ISM) with increasing halo mass. Moreover, we find that the mean density of the H i in galaxies increases with increasing stellar mass, while the DLAs in high- and low-halo mass systems have higher column densities than those in galaxies with intermediate halo masses (∼1012 M⊙ at z = 0). These high-impact CGM DLAs in high-stellar mass systems tend to be metal poor, likely tracing smooth accretion. Overall, our results point to the CGM playing an important role in DLA studies at high redshift (z ≥ 1). However, their properties are impacted both by numerical resolution and the detailed feedback prescriptions employed in cosmological simulations, particularly that of active galactic nuclei.
The inner structure of CDM haloes -- I. A numerical convergence study
Publisher: Oxford University Press (OUP)
Date: 2003
The spatial distribution of neutral hydrogen as traced by low H i mass galaxies
Publisher: Oxford University Press (OUP)
Date: 30-10-2016
Spin transfer from dark matter to gas during halo formation
Publisher: Oxford University Press (OUP)
Date: 24-06-2022
Abstract: In the protogalactic density field, diffuse gas and collision-less cold dark matter (DM) are often assumed sufficiently mixed that both components experience identical tidal torques. However, haloes in cosmological simulations consistently end up with a higher specific angular momentum (sAM) in gas, even in simulations without radiative cooling and galaxy formation physics. We refine this result by analysing the spin distributions of gas and DM in ∼50 000 well-resolved haloes in a non-radiative cosmological simulation from the SURFS suite. The sAM of the halo gas on average ends up ∼40 per cent above that of the DM. This can be pinned down to an excess AM in the inner halo (& per cent virial radius), paralleled by a more coherent rotation pattern in the gas. We uncover the leading driver for this AM difference through a series of control simulations of a collapsing ellipsoidal top-hat, where gas and DM are initially well mixed. These runs reveal that the pressurized inner gas shells collapse more slowly, causing the DM ellipsoid to spin ahead of the gas ellipsoid. The arising torque generally transfers AM from the DM to the gas. The amount of AM transferred via this mode depends on the initial spin, the initial axes ratios, and the collapse factor. These quantities can be combined in a single dimensionless parameter, which robustly predicts the AM transfer of the ellipsoidal collapse. This simplistic model can quantitatively explain the average AM excess of the gas found in the more complex non-radiative cosmological simulation.
The H i velocity function: a test of cosmology or baryon physics?
Publisher: Oxford University Press (OUP)
Date: 05-08-2019
Abstract: Accurately predicting the shape of the H i velocity function (VF) of galaxies is regarded widely as a fundamental test of any viable dark matter model. Straightforward analyses of cosmological N-body simulations imply that the Λ cold dark matter (ΛCDM) model predicts an overabundance of low circular velocity galaxies when compared to observed H i VFs. More nuanced analyses that account for the relationship between galaxies and their host haloes suggest that how we model the influence of baryonic processes has a significant impact on H i VF predictions. We explore this in detail by modelling H i emission lines of galaxies in the shark semi-analytic galaxy formation model, built on the surfs suite of ΛCDM N-body simulations. We create a simulated ALFALFA survey, in which we apply the survey selection function and account for effects such as beam confusion, and compare simulated and observed H i velocity width distributions, finding differences of ≲ 50 per cent, orders of magnitude smaller than the discrepancies reported in the past. This is a direct consequence of our careful treatment of survey selection effects and, importantly, how we model the relationship between galaxy and halo circular velocity – the H i mass–maximum circular velocity relation of galaxies is characterized by a large scatter. These biases are complex enough that building a VF from the observed H i linewidths cannot be done reliably.
SAMI-H i: the connection between global asymmetry in the ionized and neutral atomic hydrogen gas in galaxies
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.
Effect of different amendments on rice (Oryza sativa L.) growth, yield, nutrient uptake and grain quality in Ni-contaminated soil
Publisher: Springer Science and Business Media LLC
Date: 14-06-2016
DOI: 10.1007/S11356-016-7038-X
Abstract: Rice ( Oryza sativa L.) is one of the main staple food crops which is inherently low in micronutrients, especially iron (Fe), and can lead to severe Fe deficiency in populations having higher consumption of rice. Soils polluted with nickel (Ni) can cause toxicity to rice and decreased Fe uptake by rice plants. We investigated the potential role of biochar (BC) and gravel sludge (GS), alone and in combination, for in situ immobilization of Ni in an industrially Ni-contaminated soil at original and sulfur-amended altered soil pH. Our further aim was to increase Fe bioavailability to rice plants by the exogenous application of ferrous sulfate to the Ni-immobilized soil. Application of the mixture of both amendments reduced grain Ni concentration, phytate, Phytate/Fe, Phyt/Zn molar ratios, and soil DTPA-extractable Ni. In addition, the amendment mixture increased 70 % Fe and 229 % ferritin concentrations in rice grains grown in the soil at original pH. The Fe and ferritin concentrations in S-treated soil was increased up to 113 and 383 % relative to control respectively. This enhanced Fe concentration and corresponding ferritin in rice grains can be attributed to Ni/Fe antagonism where Ni has been immobilized by GS and BC mixture. This proposed technique can be used to enhance growth, yield, and Fe biofortification in rice by reducing soil pH while in parallel in situ immobilizing Ni in polluted soil.
On the relationship between gas content, star formation, and global H i asymmetry of galaxies on the star-forming main-sequence
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.
Dynamics of substructures in warm dark-matter cosmologies
Publisher: EDP Sciences
Date: 2010
DOI: 10.1051/EAS/1044008
A correlation between spin parameter and dark matter halo mass
Publisher: EDP Sciences
Date: 2010
DOI: 10.1051/EAS/1044009
Reliable mass calculation in spherical gravitating systems
Publisher: Oxford University Press (OUP)
Date: 29-10-2019
Structural and functional studies of pyruvate carboxylase regulation by cyclic di-AMP in lactic acid bacteria
Publisher: Proceedings of the National Academy of Sciences
Date: 14-08-2017
Abstract: Cyclic di-3′,5′-adenosine monophosphate (c-di-AMP) is a broadly conserved bacterial second messenger that has been implicated in a wide range of cellular processes. We report here structural, biochemical, and functional studies on the inhibition of Lactococcus lactis pyruvate carboxylase (LlPC) by c-di-AMP. The compound has a distinct binding mode in LlPC compared with that in Listeria monocytogenes PC. Mutations of residues in the binding site can abolish c-di-AMP inhibition. LlPC is required for efficient milk acidification through its essential role in aspartate biosynthesis. The aspartate pool in L. lactis is negatively regulated by c-di-AMP, and high aspartate levels can be restored by a c-di-AMP–insensitive LlPC. LlPC has high intrinsic catalytic activity and is insensitive to acetyl-CoA activation, in contrast to other PCs.
The inner structure of ΛCDM haloes - III. Universality and asymptotic slopes
Publisher: Oxford University Press (OUP)
Date: 04-2004
CosmoDRAGoN simulations—I. Dynamics and observable signatures of radio jets in cosmological environments
Publisher: Cambridge University Press (CUP)
Date: 2023
DOI: 10.1017/PASA.2023.10
Abstract: We present the C osmological D ouble R adio A ctive G alactic N uclei (CosmoDRAGoN) project: a large suite of simulated AGN jets in cosmological environments. These environments s le the intra-cluster media of galaxy clusters that form in cosmological smooth particle hydrodynamics (SPH) simulations, which we then use as inputs for grid-based hydrodynamic simulations of radio jets. Initially conical jets are injected with a range of jet powers, speeds (both relativistic and non-relativistic), and opening angles we follow their collimation and propagation on scales of tens to hundreds of kiloparsecs, and calculate spatially resolved synthetic radio spectra in post-processing. In this paper, we present a technical overview of the project, and key early science results from six representative simulations which produce radio sources with both core- (Fanaroff-Riley Type I) and edge-brightened (Fanaroff-Riley Type II) radio morphologies. Our simulations highlight the importance of accurate representation of both jets and environments for radio morphology, radio spectra, and feedback the jets provide to their surroundings.
On the role of feedback in shaping the cosmic abundance and clustering of neutral atomic hydrogen in galaxies
Publisher: Oxford University Press (OUP)
Date: 22-11-2012
DOI: 10.1093/MNRAS/STS279
A robust measure of cosmic structure beyond the power spectrum: Cosmic filaments and the temperature of dark matter
Publisher: American Astronomical Society
Date: 20-12-2013
The Impact of Realistic Foreground and Instrument Models on 21 cm Epoch of Reionization Experiments
Publisher: American Astronomical Society
Date: 22-04-2020
The distribution of satellite galaxies: the great pancake
Publisher: Oxford University Press (OUP)
Date: 11-10-2005
Phytomanagement of heavy metals in contaminated soils using sunflower: A review
Publisher: Informa UK Limited
Date: 16-09-2016
The inner structure of ΛCDM haloes – II. Halo mass profiles and low surface brightness galaxy rotation curves
Publisher: Oxford University Press (OUP)
Date: 11-12-2004
Thermal and reionization history within a large-volume semi-analytic galaxy formation simulation
Publisher: Oxford University Press (OUP)
Date: 27-01-2023
Abstract: We predict the 21-cm global signal and power spectra during the Epoch of Reionization using the meraxes semi-analytic galaxy formation and reionization model, updated to include X-ray heating and thermal evolution of the intergalactic medium. Studying the formation and evolution of galaxies together with the reionization of cosmic hydrogen using semi-analytic models (such as M eraxes) requires N-body simulations within large volumes and high-mass resolutions. For this, we use a simulation of side-length 210 h−1 Mpc with 43203 particles resolving dark matter haloes to masses of $5\\times 10^8 \\rm{ }h^{-1}\\, \\mathrm{M_\\odot }$. To reach the mass resolution of atomically cooled galaxies, thought to be the dominant population contributing to reionization, at z = 20 of $\\sim 2\\times 10^7 \\text{ }h^{-1}\\, \\mathrm{M_\\odot }$, we augment this simulation using the darkforest Monte Carlo merger tree algorithm (achieving an effective particle count of ∼1012). Using this augmented simulation, we explore the impact of mass resolution on the predicted reionization history as well as the impact of X-ray heating on the 21-cm global signal and the 21-cm power spectra. We also explore the cosmic variance of 21-cm statistics within 703 h−3 Mpc3 sub-volumes. We find that the midpoint of reionization varies by Δz ∼ 0.8 and that the cosmic variance on the power spectrum is underestimated by a factor of 2–4 at k ∼ 0.1–0.4 Mpc−1 due to the non-Gaussian nature of the 21-cm signal. To our knowledge, this work represents the first model of both reionization and galaxy formation which resolves low-mass atomically cooled galaxies while simultaneously s ling sufficiently large scales necessary for exploring the effects of X-rays in the early Universe.
MATTER IN THE BEAM: WEAK LENSING, SUBSTRUCTURES, AND THE TEMPERATURE OF DARK MATTER
Publisher: American Astronomical Society
Date: 08-2016
Unveiling the atomic hydrogen–halo mass relation via spectral stacking
Publisher: Oxford University Press (OUP)
Date: 19-07-2021
Abstract: Measuring the H i–halo mass scaling relation (HIHM) is fundamental to understanding the role of H i in galaxy formation and its connection to structure formation. While direct measurements of the H i mass in haloes are possible using H i-spectral stacking, the reported shape of the relation depends on the techniques used to measure it (e.g. monotonically increasing with mass versus flat, mass-independent). Using a simulated H i and optical survey produced with the shark semi-analytic galaxy formation model, we investigate how well different observational techniques can recover the intrinsic, theoretically predicted, HIHM relation. We run a galaxy group finder and mimic the H i stacking procedure adopted by different surveys and find we can reproduce their observationally derived HIHM relation. However, none of the adopted techniques recover the underlying HIHM relation predicted by the simulation. We find that systematic effects in halo mass estimates of galaxy groups modify the inferred shape of the HIHM relation from the intrinsic one in the simulation, while contamination by interloping galaxies, not associated with the groups, contribute to the inferred H i mass of a halo mass bin, when using large velocity windows for stacking. The effect of contamination is maximal at $M^{\\rm }_{\\rm vir}$$\\sim 10^{12-12.5}\\rm M_{\\odot }$. Stacking methods based on summing the H i emission spectra to infer the mean H i mass of galaxies of different properties belonging to a group suffer minimal contamination but are strongly limited by the use of optical counterparts, which miss the contribution of dwarf galaxies. Deep spectroscopic surveys will provide significant improvements by going deeper while maintaining high spectroscopic completeness for ex le, the WAVES survey will recover ∼52 per cent of the total H i mass of the groups with $M^{\\rm }_{\\rm vir}$ ∼ 1014M⊙ compared to ∼21 per cent in GAMA.
The redshift evolution of the mass function of cold gas in hierarchical galaxy formation models
Publisher: Oxford University Press (OUP)
Date: 25-06-2010
Extracting galaxy merger time-scales II: a new fitting formula
Publisher: Oxford University Press (OUP)
Date: 23-10-2021
Abstract: Predicting the merger time-scale (τmerge) of merging dark matter haloes, based on their orbital parameters and the structural properties of their hosts, is a fundamental problem in gravitational dynamics that has important consequences for our understanding of cosmological structure formation and galaxy formation. Previous models predicting τmerge have shown varying degrees of success when compared to the results of cosmological N-body simulations. We build on this previous work and propose a new model for τmerge that draws on insights derived from these simulations. We find that published predictions can provide reasonable estimates for τmerge based on orbital properties at infall, but tend to underpredict τmerge inside the host virial radius (R200) because tidal stripping is neglected, and overpredict it outside R200 because the host mass is underestimated. Furthermore, we find that models that account for orbital angular momentum via the circular radius Rcirc underpredict (overpredict) τmerge for bound (unbound) systems. By fitting for the dependence of τmerge on various orbital and host halo properties, we derive an improved model for τmerge that can be applied to a merging halo at any point in its orbit. Finally, we discuss briefly the implications of our new model for τmerge for semi-analytical galaxy formation modelling.
Feeding supermassive black holes through supersonic turbulence and ballistic accretion
Publisher: Oxford University Press (OUP)
Date: 16-03-2011
Remediation of arsenic-contaminated water using agricultural wastes as biosorbents
Publisher: Informa UK Limited
Date: 27-10-2015
Galaxy and Mass Assembly (GAMA): Impact of the Group Environment on Galaxy Star Formation
Publisher: American Astronomical Society
Date: 16-04-2018
HALOGEN: a tool for fast generation of mock halo catalogues
Publisher: Oxford University Press (OUP)
Date: 29-04-2015
DOI: 10.1093/MNRAS/STV711
Cosmological constraints from Fourier phase statistics
Publisher: Oxford University Press (OUP)
Date: 28-06-2018
How does our choice of observable influence our estimation of the centre of a galaxy cluster? Insights from cosmological simulations
Publisher: Oxford University Press (OUP)
Date: 31-12-2015
The Gigaparsec WiggleZ simulations: characterizing scale-dependant bias and associated systematics in growth of structure measurements
Publisher: Oxford University Press (OUP)
Date: 24-03-2015
DOI: 10.1093/MNRAS/STV314
What can the outskirts of galaxies tell us about dark matter?
Publisher: Cambridge University Press (CUP)
Date: 03-2016
DOI: 10.1017/S1743921316011522
Abstract: Deep observations of galaxy outskirts reveal faint extended stellar components (ESCs) of streams, shells, and halos, which are ghostly remnants of the tidal disruption of satellite galaxies. We use cosmological galaxy formation simulations in Cold Dark Matter (CDM) and Warm Dark Matter (WDM) models to explore how the dark matter model influences the spatial, kinematic, and orbital properties of ESCs. These reveal that the spherically averaged stellar mass density at large galacto-centric radius can be depressed by up to a factor of ~10 in WDM models relative to the CDM model, reflecting the anticipated suppressed abundance of satellite galaxies in WDM models. However, these differences are much smaller in WDM models that are compatible with observational limits, and are comparable in size to the system-to-system variation we find within the CDM model. This suggests that it will be challenging to place limits on dark matter using only the unresolved ESC.
The Internal Kinematics Of Cold Dark Matter Haloes
Publisher: EDP Sciences
Date: 2006
DOI: 10.1051/EAS:2006041
Adaptation of Crops to Warmer Climates: Morphological and Physiological Mechanisms
Publisher: Springer International Publishing
Date: 2019
The SAMI Galaxy Survey: understanding observations of large-scale outflows at low redshift with EAGLE simulations
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.
The accretion disc particle method for simulations of black hole feeding and feedback
Publisher: Oxford University Press (OUP)
Date: 23-12-2010
Citric acid assisted phytoremediation of copper by Brassica napus L.
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.ECOENV.2015.06.020
Abstract: Use of organic acids for promoting heavy metals phytoextraction is gaining worldwide attention. The present study investigated the influence of citric acid (CA) in enhancing copper (Cu) uptake by Brassica napus L. seedlings. 6 Weeks old B. napus seedlings were exposed to different levels of copper (Cu, 0, 50 and 100µM) alone or with CA (2.5mM) in a nutrient medium for 40 days. Exposure to elevated Cu levels (50 and 100µM) significantly reduced the growth, biomass production, chlorophyll content, gas exchange attributes and soluble proteins of B. napus seedlings. In addition, Cu toxicity increased the production of hydrogen peroxide (H2O2), malondialdehyde (MDA) and electrolyte leakage (EL) in leaf and root tissues of B. napus. Activities of antioxidant enzymes such as guaiacol peroxidase (POD), superoxide dismutase (SOD), catalases (CAT), ascorbate peroxidase (APX) in root and shoot tissues of B. napus were increased in response to lower Cu concentration (50µM) but increased under higher Cu concentration (100µM). Addition of CA into nutrient medium significantly alleviated Cu toxicity effects on B. napus seedlings by improving photosynthetic capacity and ultimately plant growth. Increased activities of antioxidant enzymes in CA-treated plants seems to play a role in capturing of stress-induced reactive oxygen species as was evident from lower level of H2O2, MDA and EL in CA-treated plants. Increasing Cu concentration in the nutrient medium significantly increased Cu concentration in in B. napus tissues. Cu uptake was further increased by CA application. These results suggested that CA might be a useful strategy for increasing phytoextraction of Cu from contaminated soils.
Warm dark haloes accretion histories and their gravitational signatures
Publisher: Oxford University Press (OUP)
Date: 10-09-2014
Using velocity dispersion to estimate halo mass: Is the Local Group in tension with ΛCDM?
Publisher: Oxford University Press (OUP)
Date: 06-03-2018
DOI: 10.1093/MNRAS/STY590
Physiological and biochemical mechanisms of silicon-induced copper stress tolerance in cotton (Gossypium hirsutum L.)
Publisher: Springer Science and Business Media LLC
Date: 18-10-2016
The Three Hundred project: The gizmo-simba run
Publisher: Oxford University Press (OUP)
Date: 14-05-2022
Abstract: We introduce gizmo-simba, a new suite of galaxy cluster simulations within The Three Hundred project. The Three Hundred consists of zoom re-simulations of 324 clusters with $M_{200}\\gtrsim 10^{14.8}\\, \\mathrm{M}_\\odot$ drawn from the MultiDark-Planck N-body simulation, run using several hydrodynamic and semi-analytical codes. The gizmo-simba suite adds a state-of-the-art galaxy formation model based on the highly successful Simba simulation, mildly re-calibrated to match $z$ = 0 cluster stellar properties. Comparing to The Three Hundred zooms run with gadget-x, we find intrinsic differences in the evolution of the stellar and gas mass fractions, BCG ages, and galaxy colour–magnitude diagrams, with gizmo-simba generally providing a good match to available data at $z$ ≈ 0. gizmo-simba’s unique black hole growth and feedback model yields agreement with the observed BH scaling relations at the intermediate-mass range and predicts a slightly different slope at high masses where few observations currently lie. Gizmo-Simba provides a new and novel platform to elucidate the co-evolution of galaxies, gas, and black holes within the densest cosmic environments.
Galaxy And Mass Assembly (GAMA): Gas Fueling of Spiral Galaxies in the Local Universe. I. The Effect of the Group Environment on Star Formation in Spiral Galaxies
Publisher: American Astronomical Society
Date: 14-02-2017
Galaxy And Mass Assembly (GAMA): in search of Milky Way Magellanic Cloud analogues
Publisher: Oxford University Press (OUP)
Date: 27-06-2012
The spatial distribution of cold gas in hierarchical galaxy formation models
Publisher: Oxford University Press (OUP)
Date: 03-05-2011
SIMSPIN - Constructing mock IFS kinematic data cubes
Publisher: Cambridge University Press (CUP)
Date: 2020
DOI: 10.1017/PASA.2020.8
Abstract: We present SimSpin , a new, public, software framework for generating integral field spectroscopy (IFS) data cubes from N -body/hydrodynamical simulations of galaxies, which can be compared directly with observational datasets. SimSpin provides a consistent method for studying a galaxy’s stellar component. It can be used to explore how observationally inferred measurements of kinematics, such as the spin parameter $\\lambda_R$ , are impacted by the effects of, for ex le, inclination, seeing conditions, distance. SimSpin is written in R and has been designed to be highly modular, flexible, and extensible. It is already being used by the astrophysics community to generate IFS-like cubes and FITS files for direct comparison of simulations to observations. In this paper, we explain the conceptual framework of SimSpin how it is implemented in R and we demonstrate SimSpin ’s current capabilities, providing as an ex le a brief investigation of how numerical resolution affects how reliably we can recover the intrinsic stellar kinematics of a simulated galaxy.
The Wide Area VISTA Extra-Galactic Survey (WAVES)
Publisher: Springer International Publishing
Date: 2016
Cosmic voids in evolving dark sector cosmologies: the high-redshift universe
Publisher: Oxford University Press (OUP)
Date: 10-07-2018
Exogenous application of ethylenediamminetetraacetic acid enhanced phytoremediation of cadmium by Brassica napus L.
Publisher: Springer Science and Business Media LLC
Date: 18-06-2015
Giant Aortic Mural Thrombus
Publisher: Hindawi Limited
Date: 05-04-2016
DOI: 10.1111/JOCS.12748
Application of Transformer Models to Landslide Susceptibility Mapping
Publisher: MDPI AG
Date: 23-11-2022
DOI: 10.3390/S22239104
Abstract: Landslide susceptibility mapping (LSM) is of great significance for the identification and prevention of geological hazards. LSM is based on convolutional neural networks (CNNs) CNNs use fixed convolutional kernels, focus more on local information and do not retain spatial information. This is a property of the CNN itself, resulting in low accuracy of LSM. Based on the above problems, we use Vision Transformer (ViT) and its derivative model Swin Transformer (Swin) to conduct LSM for the selected study area. Machine learning and a CNN model are used for comparison. Fourier transform litude, feature similarity and other indicators were used to compare and analyze the difference in the results. The results show that the Swin model has the best accuracy, F1-score and AUC. The results of LSM are combined with landslide points, faults and other data analysis the ViT model results are the most consistent with the actual situation, showing the strongest generalization ability. In this paper, we believe that the advantages of ViT and its derived models in global feature extraction ensure that ViT is more accurate than CNN and machine learning in predicting landslide probability in the study area.
Ultra-Compact Dwarf Galaxies and Globular Clusters: A Review of Their Spatial and Dynamical Properties
Publisher: Springer Berlin Heidelberg
Date: 2009
An Empirical Mass Function Distribution
Publisher: American Astronomical Society
Date: 27-02-2018
Dark matter profiles and annihilation in dwarf spheroidal galaxies: prospectives for present and future γ-ray observatories - I. The classical dwarf spheroidal galaxies
Publisher: Oxford University Press (OUP)
Date: 09-11-2011
An orbital perspective on the starvation, stripping, and quenching of satellite galaxies in the eagle simulations
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.
Recent Advances in Arsenic Accumulation in Rice
Publisher: Elsevier
Date: 2019
The Three Hundred project: shapes and radial alignment of satellite, infalling, and backsplash galaxies
Publisher: Oxford University Press (OUP)
Date: 21-05-2020
Abstract: Using 324 numerically modelled galaxy clusters, we investigate the radial and galaxy–halo alignment of dark matter subhaloes and satellite galaxies orbiting within and around them. We find that radial alignment depends on distance to the centre of the galaxy cluster but appears independent of the dynamical state of the central host cluster. Furthermore, we cannot find a relation between radial alignment of the halo or galaxy shape with its own mass. We report that backsplash galaxies, i.e. objects that have already passed through the cluster radius but are now located in the outskirts, show a stronger radial alignment than infalling objects. We further find that there exists a population of well radially aligned objects passing very close to the central cluster’s centre that were found to be on highly radial orbit.
The large-scale environment from cosmological simulations – I. The baryonic cosmic web
Publisher: Oxford University Press (OUP)
Date: 12-09-2017
The tidal streams of disrupting subhaloes in cosmological dark matter haloes
Publisher: Oxford University Press (OUP)
Date: 04-2008
Hidden from view: coupled dark sector physics and small scales
Publisher: Oxford University Press (OUP)
Date: 14-07-2015
FEEDBACK FROM HIGH-MASS X-RAY BINARIES ON THE HIGH-REDSHIFT INTERGALACTIC MEDIUM: MODEL SPECTRA
Publisher: American Astronomical Society
Date: 28-01-2013
Self-regulated star formation and the black hole-galaxy bulge relation
Publisher: Oxford University Press (OUP)
Date: 31-03-2011
An efficient hybrid method to produce high-resolution large-volume dark matter simulations for semi-analytic models of reionization
Publisher: Oxford University Press (OUP)
Date: 22-10-2020
Abstract: Resolving faint galaxies in large volumes is critical for accurate cosmic reionization simulations. While less demanding than hydrodynamical simulations, semi-analytic reionization models still require very large N-body simulations in order to resolve the atomic cooling limit across the whole reionization history within box sizes ${\\gtrsim}100 \\, h^{-1}\\, \\rm Mpc$. To facilitate this, we extend the mass resolution of N-body simulations using a Monte Carlo algorithm. We also propose a method to evolve positions of Monte Carlo haloes, which can be an input for semi-analytic reionization models. To illustrate, we present an extended halo catalogue that reaches a mass resolution of $M_\\text{halo} = 3.2 \\times 10^7 \\, h^{-1} \\, \\text{M}_\\odot$ in a $105 \\, h^{-1}\\, \\rm Mpc$ box, equivalent to an N-body simulation with ∼68003 particles. The resulting halo mass function agrees with smaller volume N-body simulations with higher resolution. Our results also produce consistent two-point correlation functions with analytic halo bias predictions. The extended halo catalogues are applied to the meraxes semi-analytic reionization model, which improves the predictions on stellar mass functions, star formation rate densities, and volume-weighted neutral fractions. Comparison of high-resolution large-volume simulations with both small-volume and low-resolution simulations confirms that both low-resolution and small-volume simulations lead to reionization ending too rapidly. Lingering discrepancies between the star formation rate functions predicted with and without our extensions can be traced to the uncertain contribution of satellite galaxies.
Large-scale outflows in galaxies
Publisher: Oxford University Press (OUP)
Date: 17-05-2011
Too small to succeed: the difficulty of sustaining star formation in low-mass haloes
Publisher: Oxford University Press (OUP)
Date: 08-02-2017
DOI: 10.1093/MNRAS/STX315
Abstract: We present high-resolution simulations of an isolated dwarf spheroidal (dSph) galaxy between redshifts z ∼ 10 and z ∼ 4, the epoch when several Milky Way dSph satellites experienced extended star formation, in order to understand in detail the physical processes which affect a low-mass halo's ability to retain gas. It is well established that supernova feedback is very effective at expelling gas from a 3 × 107 M⊙ halo, the mass of a typical redshift 10 progenitor of a redshift 0 halo with mass ∼109 M⊙. We investigate the conditions under which such a halo is able to retain sufficient high-density gas to support extended star formation. In particular, we explore the effects of: an increased relative concentration of the gas compared to the dark matter a higher concentration dark matter halo significantly lower supernova rates enhanced metal cooling due to enrichment from earlier supernovae. We show that disc-like gas distributions retain more gas than spherical ones, primarily due to the shorter gas cooling times in the disc. However, a significant reduction in the number of supernovae compared to that expected for a standard initial mass function is still needed to allow the retention of high-density gas. We conclude that the progenitors of the observed dSphs would only have retained the gas required to sustain star formation if their mass, concentration and gas morphology were already unusual for those of a dSph-mass halo progenitor by a redshift of 10.
Cosmic evolution of the atomic and molecular gas contents of galaxies
Publisher: Oxford University Press (OUP)
Date: 03-11-2011
On the stability of satellite planes - I. Effects of mass, velocity, halo shape and alignment
Publisher: Oxford University Press (OUP)
Date: 19-10-2017
Simulations of momentum feedback by black hole winds
Publisher: Oxford University Press (OUP)
Date: 21-02-2010
Star cluster evolution in dark matter dominated galaxies
Publisher: Elsevier BV
Date: 2010
DARK MATTER HALO PROFILES IN SCALE-FREE COSMOLOGIES
Publisher: WORLD SCIENTIFIC
Date: 05-2008
From the far-ultraviolet to the far-infrared – galaxy emission at 0 ≤ z ≤ 10 in the shark semi-analytic model
Publisher: Oxford University Press (OUP)
Date: 02-09-2019
Abstract: We combine the shark semi-analytic model of galaxy formation with the prospect software tool for spectral energy distribution (SED) generation to study the multiwavelength emission of galaxies from the far-ultraviolet (FUV) to the far-infrared (FIR) at 0 ≤ z ≤ 10. We produce a physical model for the attenuation of galaxies across cosmic time by combining a local Universe empirical relation to compute the dust mass of galaxies from their gas metallicity and mass, attenuation curves derived from radiative transfer calculations of galaxies in the eagle hydrodynamic simulation suite, and the properties of shark galaxies. We are able to produce a wide range of galaxies, from the z = 8 star-forming galaxies with almost no extinction, z = 2 submillimetre galaxies, down to the normal star-forming and red-sequence galaxies at z = 0. Quantitatively, we find that shark reproduces the observed (i) z = 0 FUV-to-FIR, (ii) 0 ≤ z ≤ 3 rest-frame K-band, and (iii) 0 ≤ z ≤ 10 rest-frame FUV luminosity functions, (iv) z ≤ 8 UV slopes, (v) the FUV-to-FIR number counts (including the widely disputed 850 μm), (vi) redshift distribution of bright $850\\, \\mu$m galaxies, and (vii) the integrated cosmic SED from z = 0 to 1 to an unprecedented level. This is achieved without the need to invoke changes in the stellar initial mass function, dust-to-metal mass ratio, or metal enrichment time-scales. Our model predicts star formation in galaxy discs to dominate in the FUV-to-optical, while bulges dominate at the NIR at all redshifts. The FIR sees a strong evolution in which discs dominate at z ≤ 1 and starbursts (triggered by both galaxy mergers and disc instabilities, in an even mix) dominate at higher redshifts, even out to z = 10.
Spurious haloes and discreteness-driven relaxation in cosmological simulations
Publisher: Oxford University Press (OUP)
Date: 08-07-2016
4MOST Consortium Survey 7: Wide-Area VISTA Extragalactic Survey (WAVES)
Publisher: European Southern Observatory (ESO)
Date: 2019
Cadmium phytoremediation potential of Brassica crop species: A review
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.SCITOTENV.2018.03.104
Abstract: Cadmium (Cd) is a highly toxic metal released into the environment through anthropogenic activities. Phytoremediation is a green technology used for the stabilization or remediation of Cd-contaminated soils. Brassica crop species can produce high biomass under a range of climatic and growing conditions, allowing for considerable uptake and accumulation of Cd, depending on species. These crop species can tolerate Cd stress via different mechanisms, including the stimulation of the antioxidant defense system, chelation, compartmentation of Cd into metabolically inactive parts, and accumulation of total amino-acids and osmoprotectants. A higher Cd-stress level, however, overcomes the defense system and may cause oxidative stress in Brassica species due to overproduction of reactive oxygen species and lipid peroxidation. Therefore, numerous approaches have been followed to decrease Cd toxicity in Brassica species, including selection of Cd-tolerant cultivars, the use of inorganic and organic amendments, exogenous application of soil organisms, and employment of plant-growth regulators. Furthermore, the coupling of genetic engineering with cropping may also help to alleviate Cd toxicity in Brassica species. However, several field studies demonstrated contrasting results. This review suggests that the combination of Cd-tolerant Brassica cultivars and the application of soil amendments, along with proper agricultural practices, may be the most efficient means of the soil Cd phytoattenuation. Breeding and selection of Cd-tolerant species, as well as species with higher biomass production, might be needed in the future when aiming to use Brassica species for phytoremediation.
Comparative efficiency of peanut shell and peanut shell biochar for removal of arsenic from water
Publisher: Springer Science and Business Media LLC
Date: 04-05-2019
DOI: 10.1007/S11356-019-05185-Z
Abstract: Contamination of surface water and groundwater streams with carcinogenic chemicals such as arsenic (As) has been a major environmental issue worldwide, and requires significant attention to develop new and low-cost sorbents to treat As-polluted water. In the current study, arsenite (As(III)) and arsenate (As(V)) removal efficiency of peanut shell biochar (PSB) was compared with peanut shell (PS) in aqueous solutions. Sorption experiments showed that PSB possessed relatively higher As removal efficiency than PS, with 95% As(III) (at pH 7.2) and 99% As(V) (at pH 6.2) with 0.6 g L
Erratum to: Cost-effective enhanced iron bioavailability in rice grain grown on calcareous soil by sulfur mediation and its effect on heavy metals mineralization
Publisher: Springer Science and Business Media LLC
Date: 02-12-2016
The formation of entropy cores in non-radiative galaxy cluster simulations: smoothed particle hydrodynamics versus adaptive mesh refinement
Publisher: Oxford University Press (OUP)
Date: 17-04-2014
DOI: 10.1093/MNRAS/STU418
5-Aminolevulinic Acid-Induced Heavy Metal Stress Tolerance and Underlying Mechanisms in Plants
Publisher: Springer Science and Business Media LLC
Date: 29-10-2018
Dark-ages Reionization and Galaxy formation simulation – I. The dynamical lives of high-redshift galaxies
Publisher: Oxford University Press (OUP)
Date: 30-03-2016
DOI: 10.1093/MNRAS/STW674
On the Correlation between Spin Parameter and Halo Mass
Publisher: American Astronomical Society
Date: 10-05-2008
DOI: 10.1086/586702
Large-scale structure topology in non-standard cosmologies: impact of dark sector physics
Publisher: Oxford University Press (OUP)
Date: 16-02-2017
DOI: 10.1093/MNRAS/STX375
From stellar haloes to intracluster light: the physics of the Intra-Halo Stellar Component in cosmological hydrodynamical simulations
Publisher: Oxford University Press (OUP)
Date: 21-04-2020
Abstract: We study the Intra-Halo Stellar Component (IHSC) of Milky Way-mass systems up to galaxy clusters in the Horizon-AGN cosmological hydrodynamical simulation. We identify the IHSC using an improved phase-space galaxy finder algorithm which provides an adaptive, physically motivated, and shape-independent definition of this stellar component, that can be applied to haloes of arbitrary masses. We explore the IHSC mass fraction – total halo’s stellar mass, $f_{M_{*,\\mathrm{IHSC}}} - M_{*}$, relation, and the physical drivers of its scatter. We find that on average, the $f_{M_{*,\\mathrm{IHSC}}}$ increases with total stellar mass, with the scatter decreasing strongly with mass from 2 dex at $M_{*,\\mathrm{tot}}\\simeq 10^{11}\\, \\mathrm{M}_\\odot$ to 0.3 dex at group masses. At high masses, $M_{*,\\mathrm{tot}}\\gt 10^{11.5}\\, \\mathrm{M}_\\odot$, $f_{M_{*,\\mathrm{IHSC}}}$ increases with the number of substructures, and with the mass ratio between the central galaxy and largest satellite, at fixed M*, tot. From mid-size groups and systems below $M_{*,\\mathrm{tot}}\\lt 10^{12}\\, \\mathrm{M}_\\odot$, we find that the central galaxy’s stellar rotation-to-dispersion velocity ratio, V/σ, displays the strongest (anti)-correlation with $f_{M_{*,\\mathrm{IHSC}}}$ at fixed M*, tot of all the galaxy and halo properties explored, transitioning from $f_{M_{*,\\mathrm{IHSC}}}\\lt 0.1$ per cent for high V/σ, to $f_{M_{*,\\mathrm{IHSC}}}\\approx 5$ per cent for low V/σ galaxies. By studying the $f_{M_{*,\\mathrm{IHSC}}}$ temporal evolution, we find that, in the former, mergers not always take place, but if they did, they happened early (z & 1), while the high $f_{M_{*,\\mathrm{IHSC}}}$ population displays a much more active merger history. In the case of massive groups and galaxy clusters, $M_{*,\\mathrm{tot}}\\gtrsim 10^{12}\\, \\mathrm{M}_\\odot$, a fraction $f_{M_{*,\\mathrm{IHSC}}}\\approx 10-20$ per cent is reached at z ≈ 1 and then they evolve across lines of constant $f_{M_{*,\\mathrm{IHSC}}}$ modulo some small perturbations. Because of the limited simulation’s volume, the latter is only tentative and requires a larger s le of simulated galaxy clusters to confirm.
Modelling supermassive black hole growth: towards an improved sub-grid prescription
Publisher: Oxford University Press (OUP)
Date: 09-03-2012
The dynamical state of dark matter haloes in cosmological simulations - I. Correlations with mass assembly history
Publisher: Oxford University Press (OUP)
Date: 24-10-2011
The impact of stellar and AGN feedback on halo-scale baryonic and dark matter accretion in the eagle simulations
Publisher: Oxford University Press (OUP)
Date: 14-08-2020
Abstract: We use the eagle suite of hydrodynamical simulations to analyse accretion rates (and the breakdown of their constituent channels) on to haloes over cosmic time, comparing the behaviour of baryons and dark matter (DM). We also investigate the influence of sub-grid baryon physics on halo-scale inflow, specifically the consequences of modelling radiative cooling, as well as feedback from stars and active galactic nuclei (AGNs). We find that variations in halo baryon fractions at fixed mass (particularly their circumgalactic medium gas content) are very well correlated with variations in the baryon fraction of accreting matter, which we show to be heavily suppressed by stellar feedback in low-mass haloes, Mhalo ≲ 1011.5 M⊙. Breaking down accretion rates into first infall, recycled, transfer, and merger components, we show that baryons are much more likely to be smoothly accreted than to have originated from mergers when compared to DM, finding (averaged across halo mass) a merger contribution of $\\approx 6{{\\ \\rm per\\ cent}}$ for baryons, and $\\approx 15{{\\ \\rm per\\ cent}}$ for DM at z ≈ 0. We also show that the breakdown of inflow into different channels is strongly dependent on sub-grid physics, particularly the contribution of recycled accretion (accreting matter that has been previously ejected from progenitor haloes). Our findings highlight the dual role that baryonic feedback plays in regulating the evolution of galaxies and haloes: by (i) directly removing gas from haloes, and (ii) suppressing gas inflow to haloes.
A novel JEAnS analysis of the Fornax dwarf using evolutionary algorithms: Mass follows light with signs of an off-centre merger
Publisher: Oxford University Press (OUP)
Date: 20-05-2017
xGASS: Robust quantification of asymmetries in global H i spectra and their relationship to environmental processes
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.
Alleviative role of exogenously applied mannitol in maize cultivars differing in chromium stress tolerance
Publisher: Springer Science and Business Media LLC
Date: 03-01-2019
DOI: 10.1007/S11356-018-3970-2
Abstract: A pot experiment was performed to examine the role of foliar applied mannitol (M) in chromium (Cr) stress alleviation in different maize cultivars. Two maize cultivars, one tolerant (6103) and one sensitive (9108) to chromium stress, were grown in soil treated with three concentrations of Cr (0, 5, and 10 mg kg
The three hundred project: galaxy cluster mergers and their impact on the stellar component of brightest cluster galaxies
Publisher: Oxford University Press (OUP)
Date: 31-01-2022
Abstract: Using the data set of the three hundred project, i.e. a suite of 324 hydrodynamical resimulations of cluster-sized haloes, we study galaxy cluster mergers and their effect on colour and luminosity changes of their brightest cluster galaxies (BCG). We track the main progenitor of each halo at z = 0 and search for merger situations based on its mass accretion history, defining mergers as very rapid increases in the halo mass. Based upon the evolution of the dynamical state of the cluster we define a pre- and post-merger phase. We create a list of all these events and statistically study their mass ratio and time-scales, with the former verifying that all instances are in fact major mergers. By comparing to a control s le of clusters without mergers, we study the effect mergers have on the stellar component of the BCG. Analysing the mass, age, and metallicity of the BCG stellar particles, we find that the stellar content of BCGs grows significantly during mergers and, even though the main growth mechanism is the accretion of older stars, there is even a burst in star formation induced by the merger. In our simulations, BCGs in mergers form in median around 70 per cent more stars than those normally growing, although this depends on the radius considered for defining the BCG. Regarding observable properties, we see an increase in SDSS-u luminosity of 20 per cent during mergers, accompanied by a slightly slower increase of the galaxy g − r colour as compared to the control s le.
Global H i asymmetries in IllustrisTNG: a diversity of physical processes disturb the cold gas in galaxies
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.
SURFS: Riding the waves with Synthetic UniveRses For Surveys
Publisher: Oxford University Press (OUP)
Date: 10-01-2018
DOI: 10.1093/MNRAS/STY061
4MOST: Project overview and information for the First Call for Proposals
Publisher: European Southern Observatory (ESO)
Date: 2019
The Three Hundred Project: The stellar angular momentum evolution of cluster galaxies
Publisher: EDP Sciences
Date: 08-2021
DOI: 10.1051/0004-6361/202038425
Abstract: Using 324 numerically modelled galaxy clusters as provided by T HE T HREE H UNDRED project, we study the evolution of the kinematic properties of the stellar component of haloes on first infall. We selected objects with M star 5 × 10 10 h −1 M ⊙ within 3 R 200 of the main cluster halo at z = 0 and followed their progenitors. We find that although haloes are stripped of their dark matter and gas after entering the main cluster halo, there is practically no change in their stellar kinematics. For the vast majority of our ‘galaxies’ – defined as the central stellar component found within the haloes that form our s le – their kinematic properties, as described by the fraction of ordered rotation, and their position in the specific stellar angular momentum−stellar mass plane j star − M star are mostly unchanged by the influence of the central host cluster. However, for a small number of infalling galaxies, stellar mergers and encounters with remnant stellar cores close to the centre of the main cluster, particularly during pericentre passage, are able to spin up their stellar component by z = 0.
HMFcalc: An online tool for calculating dark matter halo mass functions
Publisher: Elsevier BV
Date: 11-2013
Dark matter halo profiles in scale-free cosmologies
Publisher: Oxford University Press (OUP)
Date: 04-2008
Gravitational lensing in WDM cosmologies: The cross-section for giant arcs
Publisher: Oxford University Press (OUP)
Date: 15-05-2014
DOI: 10.1093/MNRAS/STU705
Revealing the physical properties of gas accreting to haloes in the EAGLE simulations
Publisher: Oxford University Press (OUP)
Date: 17-04-2021
Abstract: The inflow of cosmological gas on to haloes, while challenging to directly observe and quantify, plays a fundamental role in the baryon cycle of galaxies. Using the eagle suite of hydrodynamical simulations, we present a thorough exploration of the physical properties of gas accreting on to haloes – namely, its spatial characteristics, density, temperature, and metallicity. Classifying accretion as ‘hot’ or ‘ cold’ based on a temperature cut-off 105.5 K, we find that the covering fraction (fcov) of cold-mode accreting gas is significantly lower than the hot-mode, with z = 0 fcov values of ${\\approx}50{{\\ \\rm per\\ cent}}$ and ${\\approx}80{{\\ \\rm per\\ cent}}$, respectively. Active galactic nucleus (AGN) feedback in eagle reduces inflow fcov values by ${\\approx}10{{\\ \\rm per\\ cent}}$, with outflows decreasing the solid angle available for accretion flows. Classifying inflow by particle history, we find that gas on first-infall on to a halo is metal depleted by ≈2 dex compared to pre-processed gas, which we find to mimic the circum-galactic medium (CGM) in terms of metal content. We also show that high (low) halo-scale gas accretion rates are associated with metal-poor (rich) CGM in haloes below $10^{12}\\, \\mathrm{M}_{\\odot }$, and that variation in halo-scale gas accretion rates may offer a physical explanation for the enhanced scatter in the star-forming main sequence at low (${\\lesssim}10^{9}\\, \\mathrm{M}_{\\odot }$) and high (${\\gtrsim}10^{10}\\, \\mathrm{M}_{\\odot }$) stellar masses. Our results highlight how gas inflow influences several halo- and galaxy-scale properties, and the need to combine kinematic and chemical data in order to confidently break the degeneracy between accreting and outgoing gas in CGM observations.
The Three Hundred Project: The Influence of Environment on Simulated Galaxy Properties
Publisher: American Astronomical Society
Date: 30-11-2018
Thermal instabilities in cooling galactic coronae: fuelling star formation in galactic discs
Publisher: Oxford University Press (OUP)
Date: 27-07-2013
DOI: 10.1093/MNRAS/STT977
Confronting cold dark matter predictions with observed galaxy rotations
Publisher: American Astronomical Society
Date: 15-03-2013
Erratum: The physical drivers of the atomic hydrogen–halo mass relation
Publisher: Oxford University Press (OUP)
Date: 26-03-2021
Galaxy formation & dark matter modelling in the era of the square kilometre array
Publisher: Sissa Medialab
Date: 29-05-2015
DOI: 10.22323/1.215.0133
How well do we know the halo mass function?
Publisher: Oxford University Press (OUP)
Date: 10-07-2013
Quenching star formation in cluster galaxies
Publisher: Oxford University Press (OUP)
Date: 03-04-2014
DOI: 10.1093/MNRAS/STU389
Cosmic voids in evolving dark sector cosmologies: the low-redshift universe
Publisher: Oxford University Press (OUP)
Date: 22-03-2017
DOI: 10.1093/MNRAS/STX657
SimSpin v2.6.0 - Constructing synthetic spectral IFU cubes for comparison with observational surveys
Publisher: Cambridge University Press (CUP)
Date: 2023
DOI: 10.1017/PASA.2023.47
Which galaxies dominate the neutral gas content of the Universe?
Publisher: Oxford University Press (OUP)
Date: 16-03-2014
DOI: 10.1093/MNRAS/STU266
The H i mass function as a probe of photoionization feedback on low-mass galaxy formation
Publisher: Oxford University Press (OUP)
Date: 31-08-2015
Modelling Galaxy Populations in the Era of Big Data
Publisher: Cambridge University Press (CUP)
Date: 05-2014
DOI: 10.1017/S1743921314010710
Abstract: The coming decade will witness a deluge of data from next generation galaxy surveys such as the Square Kilometre Array and Euclid. How can we optimally and robustly analyse these data to maximise scientific returns from these surveys? Here we discuss recent work in developing both the conceptual and software frameworks for carrying out such analyses and their application to the dark matter halo mass function. We summarise what we have learned about the HMF from the last 10 years of precision CMB data using the open-source HMFcalc framework, before discussing how this framework is being extended to the full Halo Model.
THE OBSERVEDM-σ RELATIONS IMPLY THAT SUPER-MASSIVE BLACK HOLES GROW BY COLD CHAOTIC ACCRETION
Publisher: American Astronomical Society
Date: 11-06-2012
Erratum: The large-scale environment from cosmological simulations I. The baryonic cosmic web
Publisher: Oxford University Press (OUP)
Date: 15-11-2017
On the relation between the radial alignment of dark matter subhaloes and host mass in cosmological simulations
Publisher: Oxford University Press (OUP)
Date: 05-2008
The anisotropic distribution of satellite galaxies
Publisher: Oxford University Press (OUP)
Date: 11-2008
Galactic chimney sweeping: the effect of ‘gradual’ stellar feedback mechanisms on the evolution of dwarf galaxies
Publisher: Oxford University Press (OUP)
Date: 02-09-2019
Abstract: We investigate the impact of time-resolved ‘gradual’ stellar feedback processes in high redshift dwarf spheroidal galaxies. Here ‘gradual’ feedback refers to in idual stellar feedback events which deposit energy over a period of time. We conduct high-resolution hydrodynamical simulations of dwarf spheroidal galaxies with halo masses of 107–108 M⊙, based on z = 6 progenitors of the Milky Way’s dwarf spheroidal galaxies. We also include a novel feedback prescription for in idual massive stars, which includes stellar winds and an HMXB (high mass X-ray binary) phase, on top of supernovae. We find the mass of gas unbound across a 1 Gyr starburst is uniformly lowered if gradual feedback mechanisms are included across the range of metallicities, halo concentration parameters, and galaxy masses studied here. Furthermore, we find including gradual feedback in the smallest galaxies delays the unbinding of the majority of the gas and facilitates the production of ‘chimneys’ in the dense shell surrounding the feedback generated hot, pressurized ‘superbubble’. These ‘chimneys’ vent hot gas from the galaxy interior, lowering the temperature of the central 10 kpc of the gaseous halo. Additionally, we find radiative cooling has little effect on the energetics of simulations that include a short, violent starburst compared with those that have a longer, less concentrated starburst. Finally, we investigate the relative impact of HMXB feedback and stellar winds on our results, finding the ubiquity of stellar winds throughout each starburst makes them a defining factor in the final state of the interstellar medium.
Silicon (Si) alleviates cotton (Gossypium hirsutum L.) from zinc (Zn) toxicity stress by limiting Zn uptake and oxidative damage
Publisher: Springer Science and Business Media LLC
Date: 18-12-2015
DOI: 10.1007/S11356-014-3938-9
Abstract: Silicon (Si) is as an important fertilizer element, which has been found effective in enhancing plant tolerance to variety of biotic and a-biotic stresses. This study investigates the Si potential to alleviate zinc (Zn) toxicity stress in cotton (Gossypium hirsutum L.). Cotton plants were grown in hydroponics and exposed to different Zn concentration, 0, 25, and 50 μM, alone and/or in combination with 1 mM Si. Incremental Zn concentration in growth media instigated the cellular oxidative damage that was evident from elevated levels of hydrogen peroxide (H2O2), electrolyte leakage, and malondialdehyde (MDA) and consequently inhibited cotton growth, biomass, chlorophyll pigments, and photosynthetic process. Application of Si significantly suppressed Zn accumulation in various plant parts, i.e., roots, stems, and leaves and thus promoted biomass, photosynthetic, growth parameters, and antioxidant enzymes activity of Zn-stressed as well unstressed plants. In addition, Si reduced the MDA and H2O2 production and electrolyte leakage suggesting its role in protecting cotton plants from Zn toxicity-induced oxidative damage. Thus, the study indicated that exogenous Si application could improve growth and development of cotton crop experiencing Zn toxicity stress by limiting Zn bioavailability and oxidative damage.
Exogenously applied growth regulators protect the cotton crop from heat-induced injury by modulating plant defense mechanism
Publisher: Springer Science and Business Media LLC
Date: 20-11-2018
DOI: 10.1038/S41598-018-35420-5
Abstract: Episodes of extremely high temperature during reproductive stages of cotton crops are common in many parts of the world. Heat stress negatively influences plant growth, physiology and ultimately lint yield. This study attempts to modulate heat-induced damage to cotton crops via application of growth regulators e.g. hydrogen peroxide (H 2 O 2 30ppm), salicylic acid (SA 50ppm), moringa leaf extract (MLE 30 times diluted) and ascorbic acid (ASA 70ppm). Cotton plants were exposed to different thermal regimes by staggering sowing time (field) or exposing to elevated temperatures (38/24 °C and 45/30 °C) for one week during reproductive growth stages (glasshouse). Elevated temperatures significantly induced lipid membrane damage, which was evident from an increased malondialdehyde (MDA) level in cotton leaves. Heat-stressed plants also experienced a significant reduction in leaf chlorophyll contents, net photosynthetic rate and lint yield. Hydrogen peroxide outclassed all the other regulators in increasing leaf SOD, CAT activity, chlorophyll contents, net photosynthetic rate, number of sympodial branches, boll weight and fiber quality components. For ex le, hydrogen peroxide improved boll weight of heat stressed plants by 32% (supra), 12% (sub) under glasshouse and 18% (supra) under field conditions compared with water treated plants under the same temperatures. Growth regulators, specifically, H 2 O 2 protected physiological processes of cotton from heat-induced injury by capturing reactive oxygen species and modulating antioxidant enzymes. Thus, cotton performance in the future warmer climates may be improved through regulation (endogenous) or application (exogenous) hormones during reproductive phases.
Pre-processing, group accretion, and the orbital trajectories of associated subhaloes
Publisher: Oxford University Press (OUP)
Date: 28-12-2021
Abstract: We use a high-resolution cosmological dark matter-only simulation to study the orbital trajectories of haloes and subhaloes in the environs of isolated hosts. We carefully tally all apsis points and use them to distinguish haloes that are infalling for the first time from those that occupy more evolved orbits. We find that roughly 21 per cent of resolved subhaloes within a host’s virial radius are currently on first infall, and have not yet reached their first orbital pericentre roughly 44 per cent are still approaching their first apocentre after infall. For the range of host masses studied, roughly half of all accreted systems were pre-processed prior to infall, and about 20 per cent were accreted in groups. We confirm that the entire population of accreted subhaloes – often referred to as ‘associated’ subhaloes – extends far beyond the virial radii of their hosts, with roughly half currently residing at distances that exceed ≈1.2 × r200. Many of these backsplash haloes have gained orbital energy since infall, and occupy extreme orbits that carry them well past their initial turnaround radii. Such extreme orbits are created during the initial accretion and dissolution of loosely bound groups, but also through penetrating encounters between subhaloes on subsequent orbits. The same processes may also give rise to unexpectedly abrupt losses of orbital energy. These effects combine, giving rise to a large variation in the ratio of sequent apocentres for accreted systems. We find that, within two virial radii from host centres, the concentrations of first-infall haloes are remarkably similar to those of isolated field haloes, whereas backsplash haloes, as well as systems that were pre-processed, are considerably more concentrated.
Novel Adaptive softening for collisionlessN-body simulations: eliminating spurious haloes
Publisher: Oxford University Press (OUP)
Date: 15-02-2016
DOI: 10.1093/MNRAS/STW251
Self‐Consistent Massive Disks in Triaxial Dark Matter Halos
Publisher: American Astronomical Society
Date: 20-09-2007
DOI: 10.1086/520843
nIFTy galaxy cluster simulations VI: the dynamical imprint of substructure on gaseous cluster outskirts.
Publisher: Oxford University Press (OUP)
Date: 14-11-2019
Abstract: Galaxy cluster outskirts mark the transition region from the mildly non-linear cosmic web to the highly non-linear, virialised, cluster interior. It is in this transition region that the intra-cluster medium (ICM) begins to influence the properties of accreting galaxies and groups, as ram pressure impacts a galaxy’s cold gas content and subsequent star formation rate. Conversely, the thermodynamical properties of the ICM in this transition region should also feel the influence of accreting substructure (i.e. galaxies and groups), whose passage can drive shocks. In this paper, we use a suite of cosmological hydrodynamical zoom simulations of a single galaxy cluster, drawn from the nIFTy comparison project, to study how the dynamics of substructure accreted from the cosmic web influences the thermodynamical properties of the ICM in the cluster’s outskirts. We demonstrate how features evident in radial profiles of the ICM (e.g. gas density and temperature) can be linked to strong shocks, transient and short-lived in nature, driven by the passage of substructure. The range of astrophysical codes and galaxy formation models in our comparison are broadly consistent in their predictions (e.g. agreeing when and where shocks occur, but differing in how strong shocks will be) this is as we would expect of a process driven by large-scale gravitational dynamics and strong, inefficently radiating, shocks. This suggests that mapping such shock structures in the ICM in a cluster’s outskirts (via e.g. radio synchrotron emission) could provide a complementary measure of its recent merger and accretion history.
Role of mineral nutrition in alleviation of heat stress in cotton plants grown in glasshouse and field conditions
Publisher: Springer Science and Business Media LLC
Date: 10-09-0031
DOI: 10.1038/S41598-019-49404-6
Abstract: Coincidence of high temperature with terminal reproductive pheno-stages of cotton is chief constraint to achieve yield potential. This high temperature interfere plant defensive system, physiological process, water relations and lint yield production. In this study, we modulated the detrimental outcomes of heat stress on cotton through the foliar spray of nutrients. Cotton crop was exposed to sub-optimal and supra-optimal thermal regimes for a period of one week at squaring, flowering and boll formation stages under glass house and field conditions. Foliar spray of potassium (K-1.5%), zinc (Zn-0.2%) and boron (B-0.1%) were applied at three reproductive stages one day prior to expose high temperature regimes. High temperature increased lipid membrane damage through increased malondialdehyde (MDA) contents in cotton leaves. High temperature stress also reduced leaf chlorophyll contents, net photosynthetic rate, stomatal conductance, water potential, averaged boll weight (g) and seed cotton yield per plant. Various nutrients variably influenced growth and physiology of heat-stressed cotton plants. Zinc outclassed all other nutrients in increasing leaf SOD, CAT, POX, AsA, TPC activity, chlorophyll contents, net photosynthetic rate, stomatal conductance, water potential, boll weight and seed cotton yield per plant. For ex le, zinc improved seed cotton yield under supra-optimal thermal regime by 17% and under sub-optimal thermal regime by 12% of glasshouse study while 19% under high temperature sowing dates of field study than the water treated plants under the same temperatures. Conclusively, increasing intensities of temperature adversely affected the recorded responses of cotton and exogenous application of Zn efficaciously alleviated heat induced perturbations. Moreover, exogenous nutrients mediated upregulations in physiochemical attributes induced heat tolerance at morphological level.
Simulating feedback from nuclear clusters: the impact of multiple sources
Publisher: Oxford University Press (OUP)
Date: 22-11-2015
Observing merger trees in a new light
Publisher: Cambridge University Press (CUP)
Date: 2018
DOI: 10.1017/PASA.2018.34
Abstract: Merger trees harvested from cosmological N -body simulations encode the assembly histories of dark matter halos over cosmic time and are a fundamental component of semi-analytical models of galaxy formation. The ability to compare the tools used to construct merger trees, namely halo finders and tree building algorithms, in an unbiased and systematic manner is critical to assess the quality of merger trees. In this paper, we present the dendrogram, a novel method to visualise merger trees, which provides a comprehensive characterisation of a halo’s assembly history—tracking subhalo orbits, halo merger events, and the general evolution of halo properties. We show the usefulness of the dendrogram as a diagnostic tool of merger trees by comparing halo assembly simulation analysed with three different halo finders—VELOCI raptor , AHF, and R ockstar —and their associated tree builders. Based on our analysis of the resulting dendrograms, we highlight how they have been used to motivate improvements to VELOCI raptor . The dendrogram software is publicly available online, at: hyspoulton/MergerTree-Dendrograms .
Interactive effects of drought and heat stresses on morpho-physiological attributes, yield, nutrient uptake and oxidative status in maize hybrids
Publisher: Springer Science and Business Media LLC
Date: 07-03-2019
DOI: 10.1038/S41598-019-40362-7
Abstract: Maize is a sensitive crop to drought and heat stresses, particularly at the reproductive stages of development. The present study investigated the in idual and interactive effects of drought (50% field capacity) and heat (38 °C/30 °C) stresses on morpho-physiological growth, yield, nutrient uptake and oxidative metabolism in two maize hybrids i.e., ‘Xida 889’ and ‘Xida 319’. The stress treatments were applied at tasseling stage for 15 days. Drought, heat and drought + heat stress caused oxidative stress by the over-production of ROS (O 2− , H 2 O 2 , OH − ) and enhanced malondialdehyde contents, which led to reduced photosynthetic components, nutrients uptake and yield attributes. The concurrent occurrence of drought and heat was more severe for maize growth than the single stress. However, both stresses induced the metabolites accumulation and enzymatic and non-enzymatic antioxidants to prevent the oxidative damage. The performance of Xida 899 was more prominent than the Xida 319. The greater tolerance of Xida 889 to heat and drought stresses was attributed to strong antioxidant defense system, higher osmolyte accumulation, and maintenance of photosynthetic pigments and nutrient balance compared with Xida 319.
Exploring neutral hydrogen and galaxy evolution with the SKA
Publisher: Sissa Medialab
Date: 29-05-2015
DOI: 10.22323/1.215.0128
Self-consistent Bulge/Disk/Halo Galaxy Dynamical Modeling Using Integral Field Kinematics
Publisher: American Astronomical Society
Date: 17-11-2017
A numerical twist on the spin parameter, λR
Publisher: Oxford University Press (OUP)
Date: 18-11-2018
The First Large Absorption Survey in H i (FLASH): I. Science goals and survey design
Publisher: Cambridge University Press (CUP)
Date: 2022
DOI: 10.1017/PASA.2022.3
Abstract: We describe the scientific goals and survey design of the First Large Absorption Survey in H i (FLASH), a wide field survey for 21-cm line absorption in neutral atomic hydrogen (H i ) at intermediate cosmological redshifts. FLASH will be carried out with the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope and is planned to cover the sky south of $\\delta \\approx +40\\,\\deg$ at frequencies between 711.5 and 999.5 MHz. At redshifts between $z = 0.4$ and $1.0$ (look-back times of 4 – 8 Gyr), the H i content of the Universe has been poorly explored due to the difficulty of carrying out radio surveys for faint 21-cm line emission and, at ultra-violet wavelengths, space-borne searches for D ed Lyman- $\\alpha$ absorption in quasar spectra. The ASKAP wide field of view and large spectral bandwidth, in combination with a radio-quiet site, will enable a search for absorption lines in the radio spectra of bright continuum sources over 80% of the sky. This survey is expected to detect at least several hundred intervening 21-cm absorbers and will produce an H i -absorption-selected catalogue of galaxies rich in cool, star-forming gas, some of which may be concealed from optical surveys. Likewise, at least several hundred associated 21-cm absorbers are expected to be detected within the host galaxies of radio sources at $0.4 z 1.0$ , providing valuable kinematical information for models of gas accretion and jet-driven feedback in radio-loud active galactic nuclei. FLASH will also detect OH 18-cm absorbers in diffuse molecular gas, megamaser OH emission, radio recombination lines, and stacked H i emission.
Seeking Observable Imprints of Small-Scale Structure on the Properties of Dark Matter Haloes
Publisher: Cambridge University Press (CUP)
Date: 2013
DOI: 10.1017/PASA.2013.32
Abstract: The characteristic prediction of the Cold Dark Matter (CDM) model of cosmological structure formation is that the Universe should contain a wealth of small-scale structure—low-mass dark matter haloes and subhaloes. However, galaxy formation is inefficient in their shallow potential wells and so we expect these low-mass haloes and subhaloes to be dark. Can we tell the difference between a Universe in which these low-mass haloes are present but dark and one in which they never formed, thereby providing a robust test of the CDM model? We address this question using cosmological N -body simulations to examine how properties of low-mass haloes that are potentially accessible to observation, such as their spatial clustering, rate of accretions and mergers onto massive galaxies, and the angular momentum content of massive galaxies, differ between a fiducial ΛCDM model and dark matter models in which low-mass halo formation is suppressed. Adopting an effective cut-off mass scale M cut below which small-scale power is suppressed in the initial conditions, we study dark matter models in which M cut varies between 5×10 9 h −1 M ⊙ and 10 11 h −1 M ⊙ , equivalent to the host haloes of dwarf and low-mass galaxies. Our results show that both the clustering strength of low-mass haloes around galaxy-mass primaries and the rate at which they merge with these primaries are sensitive to the assumed value of M cut in contrast, suppressing low-mass halo formation has little influence on the angular momentum content of galaxy-mass haloes—it is the quiescence or violence of a halo's assembly history that has a more marked effect. However, we expect that measuring the effect on spatial clustering or the merger rate is likely to be observationally difficult for realistic values of M cut , and so isolating the effect of this small-scale structure would appear to be remarkably difficult to detect, at least in the present day Universe.
Major mergers between dark matter haloes – I. Predictions for size, shape, and spin
Publisher: Oxford University Press (OUP)
Date: 11-05-2019
Major mergers between dark matter haloes – II. Profile and concentration changes
Publisher: Oxford University Press (OUP)
Date: 11-05-2019
The SAMI Galaxy Survey: Early Data Release
Publisher: Oxford University Press (OUP)
Date: 20-11-2015
On the dynamical state of galaxy clusters: insights from cosmological simulations – II.
Publisher: Oxford University Press (OUP)
Date: 06-10-2016
Recovering λR and V/σ from seeing-dominated IFS data
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.
Climbing halo merger trees with TreeFrog
Publisher: Cambridge University Press (CUP)
Date: 2019
DOI: 10.1017/PASA.2019.18
Abstract: We present T ree F rog , a massively parallel halo merger tree builder that is capable comparing different halo catalogues and producing halo merger trees. The code is written in c++11, use the MPI and OpenMP API’s for parallelisation, and includes python tools to read/manipulate the data products produced. The code correlates binding energy sorted particle ID lists between halo catalogues, determining optimal descendant rogenitor matches using multiple snapshots, a merit function that maximises the number of shared particles using pseudo-radial moments, and a scheme for correcting halo merger tree pathologies. Focusing on VELOCI raptor catalogues for this work, we demonstrate how searching multiple snapshots spanning a dynamical time significantly reduces the number of stranded halos, those lacking a descendant or a progenitor, critically correcting poorly resolved halos. We present a new merit function that improves the distinction between primary and secondary progenitors, reducing tree pathologies. We find FOF accretion rates and merger rates show similar mass ratio dependence. The model merger rates from Poole, et al. [2017, 472, 3659] agree with the measured net growth of halos through mergers.
The dynamics of subhaloes in warm dark matter models
Publisher: Oxford University Press (OUP)
Date: 05-2008
Modelling near-IR spectra and mid-IR dust emission of Mira variables at different phases
Publisher: Oxford University Press (OUP)
Date: 09-2000
Hunting for galaxies and halos in simulations with VELOCIraptor
Publisher: Cambridge University Press (CUP)
Date: 2019
DOI: 10.1017/PASA.2019.12
Abstract: We present VELOCI raptor , a massively parallel galaxy/(sub)halo finder that is also capable of robustly identifying tidally disrupted objects and separate stellar halos from galaxies. The code is written in C++11, use the Message Passing Interface (MPI) and OpenMP Application Programming Interface (API) for parallelisation, and includes python tools to read/manipulate the data products produced. We demonstrate the power of the VELOCI raptor (sub)halo finder, showing how it can identify subhalos deep within the host that have negligible density contrasts to their parent halo. We find a subhalo mass-radial distance dependence: large subhalos with mass ratios of ≳10 −2 are more common in the central regions than smaller subhalos, a result of dynamical friction and low tidal mass loss rates. This dependence is completely absent in (sub)halo finders in common use, which generally search for substructure in configuration space, yet is present in codes that track particles belonging to halos as they fall into other halos, such as hbt +. VELOCI raptor largely reproduces the dependence seen without tracking, finding a similar radial dependence to hbt + in well-resolved halos from our limited resolution fiducial simulation.
The physical drivers of the atomic hydrogen–halo mass relation
Publisher: Oxford University Press (OUP)
Date: 06-08-2020
Abstract: We use the state-of-the-art semi-analytic galaxy formation model, shark, to investigate the physical processes involved in dictating the shape, scatter, and evolution of the Hi–halo mass (HIHM) relation at 0 ≤ z ≤ 2. We compare shark with Hi clustering and spectral stacking of the HIHM relation derived from observations finding excellent agreement with the former and a deficiency of Hi in shark at Mvir ≈ 1012–13 M⊙ in the latter. In shark, we find that the Hi mass increases with the halo mass up to a critical mass of ≈1011.8 M⊙ between ≈1011 and 1013 M⊙, the scatter in the relation increases by 0.7 dex and the Hi mass decreases with the halo mass on average (till $M_{\\rm vir}\\sim 10^{12.5}\\, \\rm M_{\\odot }$, after which it starts increasing) at $M_{\\rm vir}\\gtrsim 10^{13}\\, \\rm M_{\\odot }$, the Hi content continues to increase with increasing halo mass, as a result of the increasing Hi contribution from satellite galaxies. We find that the critical halo mass of ≈1012 M⊙ is set by feedback from active galactic nuclei (AGNs) which affects both the shape and scatter of the HIHM relation, with other physical processes playing a less significant role. We also determine the main secondary parameters responsible for the scatter of the HIHM relation, namely the halo spin parameter at ${M}_{\\rm vir}\\, \\lt $ 1011.8 M⊙, and the fractional contribution from substructure to the total halo mass ($M_{\\rm h}^{\\rm sat}/M_{\\rm vir}$) for ${M}_{\\rm vir}\\, \\gt $ 1013 M⊙. The scatter at 1011.8 M⊙$\\lt \\, {M}_{\\rm vir}\\, \\lt $ 1013 M⊙ is best described by the black hole-to-stellar mass ratio of the central galaxy, reflecting the relevance of AGN feedback. We present a numerical model to populate dark matter-only simulations with Hi at 0 ≤ z ≤ 2 based solely on halo parameters that are measurable in such simulations.
A stochastic model to reproduce the star formation history of individual galaxies in hydrodynamic simulations
Publisher: Oxford University Press (OUP)
Date: 13-07-2022
Abstract: The star formation history (SFH) of galaxies is critical for understanding galaxy evolution. Hydrodynamical simulations enable us to precisely reconstruct the SFH of galaxies and establish a link to the underlying physical processes. In this work, we present a model to describe in idual galaxies’ SFHs from three simulations: TheThreeHundred, Illustris-1, and TNG100-1. This model ides the galaxy SFH into two distinct components: the ‘main sequence’ and the ‘variation’. The ‘main sequence’ part is generated by tracing the history of the SFR − M* main sequence of galaxies across time. The ‘variation’ part consists of the scatter around the main sequence, which is reproduced by fractional Brownian motions. We find that: (1) the evolution of the main sequence varies between simulations (2) fractional Brownian motions can reproduce many features of SFHs however, discrepancies still exist and (3) the variations and mass-loss rate are crucial for reconstructing the SFHs of the simulations. This model provides a fair description of the SFHs in simulations. On the other hand, by correlating the fractional Brownian motion model to simulation data, we provide a ’standard’ against which to compare simulations.
A critical review of mechanisms involved in the adsorption of organic and inorganic contaminants through biochar
Publisher: Springer Science and Business Media LLC
Date: 08-2018
THE EXTENDED STELLAR COMPONENT OF GALAXIES THE NATURE OF DARK MATTER
Publisher: American Astronomical Society
Date: 28-06-2016
Extracting galaxy merger timescales I: Tracking haloes with WhereWolf and spinning orbits with OrbWeaver
Publisher: Oxford University Press (OUP)
Date: 18-11-2019
Abstract: Hierarchical models of structure formation predict that dark matter halo assembly histories are characterised by episodic mergers and interactions with other haloes. An accurate description of this process will provide insights into the dynamical evolution of haloes and the galaxies that reside in them. Using large cosmological N-body simulations, we characterise halo orbits to study the interactions between substructure haloes and their hosts, and how different evolutionary histories map to different classes of orbits. We use two new software tools - WhereWolf, which uses halo group catalogues and merger trees to ensure that haloes are tracked accurately in dense environments, and OrbWeaver, which quantifies each halo’s orbital parameters. We demonstrate how WhereWolf improves the accuracy of halo merger trees, and we use OrbWeaver to quantify orbits of haloes. We assess how well analytical prescriptions for the merger timescale from the literature compare to measured merger timescales from our simulations and find that existing prescriptions perform well, provided the ratio of substructure-to-host mass is not too small. In the limit of small substructure-to-host mass ratio, we find that the prescriptions can overestimate the merger timescales substantially, such that haloes are predicted to survive well beyond the end of the simulation. This work highlights the need for a revised analytical prescription for the merger timescale that more accurately accounts for processes such as catastrophic tidal disruption.
Pretreatment with salicylic acid and ascorbic acid significantly mitigate oxidative stress induced by copper in cotton genotypes
Publisher: Springer Science and Business Media LLC
Date: 07-02-2015
DOI: 10.1007/S11356-015-4075-9
Abstract: Higher uptake and translocation of copper (Cu) into plant tissues can cause serious physiological and biochemical alterations in root and leaf tissues of plants. The present study investigates the ameliorative role of salicylic acid (SA) and ascorbic acid (AsA) against Cu-induced toxicity changes in cotton genotypes (two parental lines (J208, Z905) and their hybrid line (ZD14)). To study the tolerance potential against Cu (100 μM) stress, 2-week-old cotton seedlings were pretreated with 100 μM either SA or AsA for three days. Elevated Cu concentration in nutrient media increased Cu accumulation in roots and shoots of all the three cotton genotypes studied. Roots were the main Cu storage site, followed by leaves and stems. Increased cellular Cu concentration significantly inhibited the root and shoot development, although leaf growth was more sensitive toward Cu toxicity. Cu-induced oxidative stress to cotton leaves was evident from significantly increased hydrogen peroxide (H2O2) contents and lipid membrane damage. Increasing Cu translocation toward cotton leaves strongly influenced the malondialdehyde (MDA) contents, which, in turn, inhibited biomass production. SA and AsA pretreated cotton seedlings showed better growth under Cu stress. Despite increase in overall Cu uptake, the SA-pretreated seedlings could defy Cu toxicity through inhibited Cu translocation and modification in the activities of antioxidative enzymes. Whereas, tolerance to Cu-induced toxicity in AsA pretreated plants was associated with Cu exclusion from tissues and reduction of the overall Cu uptake. The present study revealed that the alleviatory role of AsA was significantly higher than SA regarding Cu stress in our experimental cotton genotypes. Furthermore, the hybrid cotton genotype (ZD14) performed well followed by J208 and Z905 in the present experimental setup.
Heating and ionization of the primordial intergalactic medium by high-mass X-ray binaries
Publisher: Oxford University Press (OUP)
Date: 14-10-2014
Stability of satellite planes in M31 II: effects of the dark subhalo population
Publisher: Oxford University Press (OUP)
Date: 28-09-2017
Does slow and steady win the race? Investigating feedback processes in giant molecular clouds
Publisher: Oxford University Press (OUP)
Date: 25-07-2018
Author Correction: Exogenously applied growth regulators protect the cotton crop from heat-induced injury by modulating plant defense mechanism
Publisher: Springer Science and Business Media LLC
Date: 27-02-2019
DOI: 10.1038/S41598-018-38076-3
Abstract: A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.
Introducing a new, robust galaxy-finder algorithm for simulations
Publisher: Oxford University Press (OUP)
Date: 08-10-2019
Morpho-physiological and micrographic characterization of maize hybrids under NaCl and Cd stress
Publisher: Springer Science and Business Media LLC
Date: 21-05-2014
nIFTy cosmology: Galaxy/halo mock catalogue comparison project on clustering statistics
Publisher: Oxford University Press (OUP)
Date: 08-07-2015
The importance of interactions for mass loss from satellite galaxies in cold dark matter haloes
Publisher: Oxford University Press (OUP)
Date: 11-05-2006
A critical review on effects, tolerance mechanisms and management of cadmium in vegetables
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.CHEMOSPHERE.2017.05.013
Abstract: Cadmium (Cd) accumulation in vegetables is an important environmental issue that threatens human health globally. Understanding the response of vegetables to Cd stress and applying management strategies may help to reduce the Cd uptake by vegetables. The aim of the present review is to summarize the knowledge concerning the uptake and toxic effects of Cd in vegetables and the different management strategies to combat Cd stress in vegetables. Leafy vegetables grown in Cd contaminated soils potentially accumulate higher concentrations of Cd, posing a threat to food commodities. The Cd toxicity decreases seed germination, growth, biomass and quality of vegetables. This reduces the photosynthesis, stomatal conductance and alteration in mineral nutrition. Toxicity of Cd toxicity also interferes with vegetable biochemistry causing oxidative stress and resulting in decreased antioxidant enzyme activities. Several management options have been employed for the reduction of Cd uptake and toxicity in vegetables. The exogenous application of plant growth regulators, proper mineral nutrition, and the use of organic and inorganic amendments might be useful for reducing Cd toxicity in vegetables. The use of low Cd accumulating vegetable cultivars in conjunction with insolubilizing amendments and proper agricultural practices might be a useful technique for reducing Cd exposure in the food chain.
SMALL SCALE STRUCTURE IN DARK MATTER MODELS AND CONSEQUENCES FOR GALAXY FORMATION
Publisher: WORLD SCIENTIFIC
Date: 05-2008
The impact of box size on the properties of dark matter haloes in cosmological simulations
Publisher: Oxford University Press (OUP)
Date: 08-2006
Shark: introducing an open source, free, and flexible semi-analytic model of galaxy formation
Publisher: Oxford University Press (OUP)
Date: 06-09-2018
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