ORCID Profile
0000-0003-3085-0922
Current Organisation
University of Western Australia
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
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.
Astronomical and Space Sciences | Cosmology and Extragalactic Astronomy
Publisher: Oxford University Press (OUP)
Date: 22-02-2017
DOI: 10.1093/MNRAS/STX441
Publisher: Oxford University Press (OUP)
Date: 29-05-2019
Publisher: Oxford University Press (OUP)
Date: 09-09-2014
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-07-2021
Publisher: Oxford University Press (OUP)
Date: 10-2002
Publisher: American Astronomical Society
Date: 04-09-2019
Publisher: Oxford University Press (OUP)
Date: 03-05-2017
Publisher: Oxford University Press (OUP)
Date: 19-12-2019
Abstract: We use data from the GAMA and GALEX surveys to demonstrate that the UV upturn, an unexpected excess of ultraviolet flux from a hot stellar component, seen in the spectra of many early-type galaxies, arises from processes internal to in idual galaxies with no measurable influence from the galaxies’ larger environment. We first define a clean s le of passive galaxies without a significant contribution to their UV flux from low-level star formation. We confirm that galaxies with the optical colours of red sequence galaxies often have signs of residual star formation, which, without other information, would prevent a convincing demonstration of the presence of UV upturns. However, by including (NUV−u) and WISE (W2–W3) colours, and FUV data where it exists, we can convincingly constrain s les to be composed of non-star-forming objects. Using such a s le, we examine GALEX photometry of low-redshift GAMA galaxies in a range of low-density environments, from groups to the general field, searching for UV upturns. We find a wide range of (NUV−r) colours, entirely consistent with the range seen – and attributed to the UV upturn – in low-redshift red sequence cluster galaxies. The range of colours is independent of group multiplicity or velocity dispersion, with isolated passive galaxies just as likely to have blue UV-to-optical colours, implying significant upturn components, as those in richer groups and in the previous data on clusters. This is supported by equivalent results for (FUV−r) colours which are clear indicators of upturn components.
Publisher: Oxford University Press (OUP)
Date: 17-08-2010
Publisher: Oxford University Press (OUP)
Date: 14-12-2021
Abstract: Active galactic nuclei (AGN) are typically identified through radio, mid-infrared, or X-ray emission or through the presence of broad and/or narrow emission lines. AGN can also leave an imprint on a galaxy’s spectral energy distribution (SED) through the re-processing of photons by the dusty torus. Using the SED fitting code ProSpect with an incorporated AGN component, we fit the far-ultraviolet to far-infrared SEDs of ∼494 000 galaxies in the D10-COSMOS field and ∼230 000 galaxies from the GAMA survey. By combining an AGN component with a flexible star formation and metallicity implementation, we obtain estimates for the AGN luminosities, stellar masses, star formation histories, and metallicity histories for each of our galaxies. We find that ProSpect can identify AGN components in 91 per cent of galaxies pre-selected as containing AGN through narrow-emission line ratios and the presence of broad lines. Our ProSpect-derived AGN luminosities show close agreement with luminosities derived for X-ray selected AGN using both the X-ray flux and previous SED fitting results. We show that incorporating the flexibility of an AGN component when fitting the SEDs of galaxies with no AGN has no significant impact on the derived galaxy properties. However, in order to obtain accurate estimates of the stellar properties of AGN host galaxies, it is crucial to include an AGN component in the SED fitting process. We use our derived AGN luminosities to map the evolution of the AGN luminosity function for 0 & z & 2 and find good agreement with previous measurements and predictions from theoretical models.
Publisher: Oxford University Press (OUP)
Date: 29-10-2019
Publisher: Oxford University Press (OUP)
Date: 14-04-2018
DOI: 10.1093/MNRAS/STY933
Publisher: Oxford University Press (OUP)
Date: 26-10-2022
Abstract: Gas-phase metallicities of galaxies are typically measured through auroral or nebular emission lines, but metallicity also leaves an imprint on the overall spectral energy distribution (SED) of a galaxy and can be estimated through SED fitting. We use the ProSpect SED fitting code with a flexible parametric star formation history and an evolving metallicity history to self-consistently measure metallicities, stellar mass, and other galaxy properties for $\\sim 90\\, 000$ galaxies from the Deep Extragalactic VIsible Legacy Survey (DEVILS) and Galaxy and Mass Assembly (GAMA) survey. We use these to trace the evolution of the mass–metallicity relation (MZR) and show that the MZR only evolves in normalization by $\\sim 0.1\\,$dex at stellar mass $M_\\star = 10^{10.5}\\, \\mathrm{M}_\\odot$. We find no difference in the MZR between galaxies with and without SED evidence of active galactic nuclei emission at low redshifts ($z$ & 0.3). Our results suggest an anticorrelation between metallicity and star formation activity at fixed stellar mass for galaxies with $M_\\star \\gt 10^{10.5}\\, \\mathrm{M}_\\odot$ for $z$ & 0.3. Using the star formation histories extracted using ProSpect we explore higher order correlations of the MZR with properties of the star formation history including age, width, and shape. We find that at a given stellar mass, galaxies with higher metallicities formed most of their mass over shorter time-scales, and before their peak star formation rate. This work highlights the value of exploring the connection of a galaxy’s current gas-phase metallicity to its star formation history in order to understand the physical processes shaping the MZR.
Publisher: Oxford University Press (OUP)
Date: 09-05-2013
DOI: 10.1093/MNRAS/STT642
Publisher: Oxford University Press (OUP)
Date: 30-05-2018
Publisher: Oxford University Press (OUP)
Date: 12-06-2013
DOI: 10.1093/MNRAS/STT929
Publisher: EDP Sciences
Date: 09-2018
DOI: 10.1051/0004-6361/201832887
Abstract: Context . Probing both star formation history and evolution of distant cluster galaxies is essential to evaluate the effect of dense environment on shaping the galaxy properties we observe today. Aims . We investigate the effect of cluster environment on the processing of the molecular gas in distant cluster galaxies. We study the molecular gas properties of two star-forming galaxies separated by 6 kpc in the projected space and belonging to a galaxy cluster selected from the Irac Shallow Cluster Survey, at a redshift z = 1.2, that is, ~ 2 Gyr after the cosmic star formation density peak. This work describes the first CO detection from 1 z 1.4 star-forming cluster galaxies with no clear reported evidence of active galactic nuclei. Methods . We exploit observations taken with the NOEMA interferometer at ~3 mm to detect CO(2−1) line emission from the two selected galaxies, unresolved by our observations. Results . Based on the CO(2−1) spectrum, we estimate a total molecular gas mass M (H 2 ) = (2.2 +0.5 0.4 ) × 10 10 M ⊙ , where fully excited gas is assumed, and a dust mass M dust 4.2 × 10 8 M ⊙ for the two blended sources. The two galaxies have similar stellar masses and H α -based star formation rates (SFRs) found in previous work, as well as a large relative velocity of ~400 km s −1 estimated from the CO(2−1) line width. These findings tend to privilege a scenario where both sources contribute to the observed CO(2−1). Using the archival Spitzer MIPS flux at 24 μ m we estimate an SFR (24 μ m) = (28 +12 −8 ) M ⊙ /yr for each of the two galaxies. Assuming that the two sources contribute equally to the observed CO(2−1), our analysis yields a depletion timescale of τ dep = (3.9 +1.4 −1.8 ) × 10 8 yr, and a molecular gas to stellar mass ratio of 0.17 ± 0.13 for each of two sources, separately. We also provide a new, more precise measurement of an unknown weighted mean of the redshifts of the two galaxies, z = 1.163 ± 0.001. Conclusions . Our results are in overall agreement with those of other distant cluster galaxies and with model predictions for main sequence (MS) field galaxies at similar redshifts. The two target galaxies have molecular gas mass and depletion times that are marginally compatible with, but smaller than those of MS field galaxies, suggesting that the molecular gas has not been sufficiently refueled. We speculate that the cluster environment might have played a role in preventing the refueling via environmental mechanisms such as galaxy harassment, strangulation, ram-pressure, or tidal stripping. Higher-resolution and higher-frequency observations will enable us to spatially resolve the two sources and possibly distinguish between different gas processing mechanisms.
Publisher: Oxford University Press (OUP)
Date: 02-03-2022
Abstract: In Galaxy And Mass Assembly Data Release 4 (GAMA DR4), we make available our full spectroscopic redshift s le. This includes 248 682 galaxy spectra, and, in combination with earlier surveys, results in 330 542 redshifts across five sky regions covering ∼250 deg2. The redshift density, is the highest available over such a sustained area, has exceptionally high completeness (95 per cent to rKiDS = 19.65 mag), and is well-suited for the study of galaxy mergers, galaxy groups, and the low redshift (z & 0.25) galaxy population. DR4 includes 32 value-added tables or Data Management Units (DMUs) that provide a number of measured and derived data products including GALEX, ESO KiDS, ESO VIKING, WISE, and HerschelSpace Observatory imaging. Within this release, we provide visual morphologies for 15 330 galaxies to z & 0.08, photometric redshift estimates for all 18 million objects to rKiDS ∼ 25 mag, and stellar velocity dispersions for 111 830 galaxies. We conclude by deriving the total galaxy stellar mass function (GSMF) and its sub- ision by morphological class (elliptical, compact-bulge and disc, diffuse-bulge and disc, and disc only). This extends our previous measurement of the total GSMF down to 106.75 M$_{\\odot } \\, h_{70}^{-2}$ and we find a total stellar mass density of ρ* = (2.97 ± 0.04) × 108 M$_{\\odot } \\, h_{70}$ Mpc−3 or $\\Omega _*=(2.17 \\pm 0.03) \\times 10^{-3} \\, h_{70}^{-1}$. We conclude that at z & 0.1, the Universe has converted 4.9 ± 0.1 per cent of the baryonic mass implied by big bang Nucleosynthesis into stars that are gravitationally bound within the galaxy population.
Publisher: Oxford University Press (OUP)
Date: 22-05-2017
Publisher: Oxford University Press (OUP)
Date: 19-12-2015
Publisher: Oxford University Press (OUP)
Date: 26-02-2021
Abstract: We present a revised measurement of the optical extragalactic background light (EBL), based on the contribution of resolved galaxies to the integrated galaxy light (IGL). The cosmic optical background radiation (COB), encodes the light generated by star formation, and provides a wealth of information about the cosmic star formation history (CSFH). We combine wide and deep galaxy number counts from the Galaxy And Mass Assembly survey (GAMA) and Deep Extragalactic VIsible Legacy Survey (DEVILS), along with the Hubble Space Telescope (HST) archive and other deep survey data sets, in nine multiwavelength filters to measure the COB in the range from 0.35 μm to 2.2 μm. We derive the luminosity density in each band independently and show good agreement with recent and complementary estimates of the optical-EBL from very high-energy (VHE) experiments. Our error analysis suggests that the IGL and γ-ray measurements are now fully consistent to within $\\sim 10{{\\ \\rm per\\ cent}}$, suggesting little need for any additional source of diffuse light beyond the known galaxy population. We use our revised IGL measurements to constrain the CSFH, and place litude constraints on a number of recent estimates. As a consistency check, we can now demonstrate convincingly, that the CSFH, stellar mass growth, and the optical-EBL provide a fully consistent picture of galaxy evolution. We conclude that the peak of star formation rate lies in the range 0.066–0.076 M⊙ yr−1 Mpc−3 at a lookback time of 9.1 to 10.9 Gyr.
Publisher: Oxford University Press (OUP)
Date: 03-06-2020
Abstract: The Galaxy And Mass Assembly Survey (GAMA) covers five fields with highly complete spectroscopic coverage (& per cent) to intermediate depths (r & 19.8 or i & 19.0 mag), and collectively spans 250 deg2 of equatorial or southern sky. Four of the GAMA fields (G09, G12, G15, and G23) reside in the European Southern Observatory (ESO) VST KiDS and ESO VISTA VIKING survey footprints, which combined with our GALEX, WISE, and Herschel data provide deep uniform imaging in the $FUV/NUV/u/g/r/i/Z/Y/J/H/K_s/W1/W2/W3/W4/P100/P160/S250/S350/S500$ bands. Following the release of KiDS DR4, we describe the process by which we ingest the KiDS data into GAMA (replacing the SDSS data previously used for G09, G12, and G15), and redefine our core optical and near-infrared (NIR) catalogues to provide a complete and homogeneous data set. The source extraction and analysis is based on the new ProFound image analysis package, providing matched-segment photometry across all bands. The data are classified into stars, galaxies, artefacts, and ambiguous objects, and objects are linked to the GAMA spectroscopic target catalogue. Additionally, a new technique is employed utilizing ProFound to extract photometry in the unresolved MIR–FIR regime. The catalogues including the full FUV–FIR photometry are described and will be fully available as part of GAMA DR4. They are intended for both standalone science, selection for targeted follow-up with 4MOST, as well as an accompaniment to the upcoming and ongoing radio arrays now studying the GAMA 23h field.
Publisher: Oxford University Press (OUP)
Date: 27-11-2021
Publisher: Oxford University Press (OUP)
Date: 24-11-2017
Publisher: Oxford University Press (OUP)
Date: 28-08-2017
Publisher: American Astronomical Society
Date: 16-04-2018
Publisher: Oxford University Press (OUP)
Date: 30-11-2016
Publisher: Oxford University Press (OUP)
Date: 24-12-2015
Publisher: American Astronomical Society
Date: 15-09-2022
Abstract: We give an overview and describe the rationale, methods, and testing of the Hubble Space Telescope (HST) Archival Legacy project “SKYSURF.” SKYSURF uses HST’s unique capability as an absolute photometer to measure the ∼0.2–1.7 μ m sky-surface brightness (sky-SB) from 249,861 WFPC2, ACS, and WFC3 exposures in ∼1400 independent HST fields. SKYSURF’s panchromatic data set is designed to constrain the discrete and diffuse UV to near-IR sky components: Zodiacal Light (ZL), Kuiper Belt Objects (KBOs), Diffuse Galactic Light (DGL), and the discrete plus diffuse Extragalactic Background Light (EBL). We outline SKYSURF’s methods to: (1) measure sky-SB levels between detected objects (2) measure the discrete EBL, most of which comes from AB≃17–22 mag galaxies and (3) estimate how much truly diffuse light may exist. Simulations of HST WFC3/IR images with known sky values and gradients, realistic cosmic ray (CR) distributions, and star plus galaxy counts were processed with nine different algorithms to measure the “Lowest Estimated Sky-SB” (LES) in each image between the discrete objects. The best algorithms recover the LES values within 0.2% when there are no image gradients, and within 0.2%–0.4% when there are 5%–10% gradients. We provide a proof of concept of our methods from the WFC3/IR F125W images, where any residual diffuse light that HST sees in excess of zodiacal model predictions does not depend on the total object flux that each image contains. This enables us to present our first SKYSURF results on diffuse light in Carleton et al.
Publisher: Oxford University Press (OUP)
Date: 19-02-2014
DOI: 10.1093/MNRAS/STU104
Publisher: SPIE
Date: 29-08-2022
DOI: 10.1117/12.2628965
Publisher: Oxford University Press (OUP)
Date: 26-04-2020
Abstract: We introduce ProSpect, a generative galaxy spectral energy distribution (SED) package that encapsulates the best practices for SED methodologies in a number of astrophysical domains. ProSpect comes with two popular families of stellar population libraries (BC03 and EMILES), and a large variety of methods to construct star formation and metallicity histories. It models dust through the use of a Charlot & Fall attenuation model, with re-emission using Dale far-infrared templates. It also has the ability to model active galactic nucleus (AGN) through the inclusion of a simple AGN and hot torus model. Finally, it makes use of MAPPINGS-III photoionization tables to produce line emission features. We test the generative and inversion utility of ProSpect through application to the Shark galaxy formation semi-analytic code, and informed by these results produce fits to the final ultraviolet to far-infrared photometric catalogues produces by the Galaxy and Mass Assembly Survey. As part of the testing of ProSpect, we also produce a range of simple photometric stellar mass approximations covering a range of filters for both observed frame and rest-frame photometry.
Publisher: Cambridge University Press (CUP)
Date: 2020
DOI: 10.1017/PASA.2019.49
Abstract: We present a detailed analysis of the radio galaxy PKS $2250{-}351$ , a giant of 1.2 Mpc projected size, its host galaxy, and its environment. We use radio data from the Murchison Widefield Array, the upgraded Giant Metre-wavelength Radio Telescope, the Australian Square Kilometre Array Pathfinder, and the Australia Telescope Compact Array to model the jet power and age. Optical and IR data come from the Galaxy And Mass Assembly (GAMA) survey and provide information on the host galaxy and environment. GAMA spectroscopy confirms that PKS $2250{-}351$ lies at $z=0.2115$ in the irregular, and likely unrelaxed, cluster Abell 3936. We find its host is a massive, ‘red and dead’ elliptical galaxy with negligible star formation but with a highly obscured active galactic nucleus dominating the mid-IR emission. Assuming it lies on the local M – $\\sigma$ relation, it has an Eddington accretion rate of $\\lambda_{\\rm EDD}\\sim 0.014$ . We find that the lobe-derived jet power (a time-averaged measure) is an order of magnitude greater than the hotspot-derived jet power (an instantaneous measure). We propose that over the lifetime of the observed radio emission ( ${\\sim} 300\\,$ Myr), the accretion has switched from an inefficient advection-dominated mode to a thin disc efficient mode, consistent with the decrease in jet power. We also suggest that the asymmetric radio morphology is due to its environment, with the host of PKS $2250{-}351$ lying to the west of the densest concentration of galaxies in Abell 3936.
Publisher: American Astronomical Society
Date: 04-01-2012
Publisher: Oxford University Press (OUP)
Date: 03-2021
Abstract: We analyse the metallicity histories of ∼4500 galaxies from the GAMA survey at z & 0.06 modelled by the SED-fitting code ProSpect using an evolving metallicity implementation. These metallicity histories, in combination with the associated star formation histories, allow us to analyse the inferred gas-phase mass–metallicity relation. Furthermore, we extract the mass–metallicity relation at a sequence of epochs in cosmic history, to track the evolving mass–metallicity relation with time. Through comparison with observations of gas-phase metallicity over a large range of redshifts, we show that, remarkably, our forensic SED analysis has produced an evolving mass–metallicity relationship that is consistent with observations at all epochs. We additionally analyse the three-dimensional mass–metallicity–SFR space, showing that galaxies occupy a clearly defined plane. This plane is shown to be subtly evolving, displaying an increased tilt with time caused by general enrichment, and also the slowing down of star formation with cosmic time. This evolution is most apparent at lookback times greater than 7 Gyr. The trends in metallicity recovered in this work highlight that the evolving metallicity implementation used within the SED-fitting code ProSpect produces reasonable metallicity results over the history of a galaxy. This is expected to provide a significant improvement to the accuracy of the SED-fitting outputs.
Publisher: American Astronomical Society
Date: 04-10-2022
Abstract: We present the first results from the HST Archival Legacy project “SKYSURF.” As described in Windhorst et al., SKYSURF utilizes the large HST archive to study the diffuse UV, optical, and near-IR backgrounds and foregrounds in detail. Here, we utilize SKYSURF’s first sky-surface-brightness measurements to constrain the level of near-IR diffuse Extragalactic Background Light (EBL) in three near-IR filters (F125W, F140W, and F160W). This is done by comparing our preliminary sky measurements of ,000 images to zodiacal light models, carefully selecting the darkest images to avoid contamination from stray light. Our sky-surface-brightness measurements have been verified to an accuracy of better than 1%, which when combined with systematic errors associated with HST, results in sky-brightness uncertainties of ∼ 2%–4% ≃ 0.005 MJy sr −1 in each image. When compared to the Kelsall et al. zodiacal model, an isotropic diffuse background of ∼30 nW m −2 sr −1 remains, whereas using the Wright zodiacal model results in no discernible diffuse background. Based primarily on uncertainties in the foreground model subtraction, we present limits on the amount of diffuse EBL of 29, 40, and 29 nW m −2 sr −1 , for F125W, F140W, and F160W, respectively. While this light is generally isotropic, our modeling at this point does not distinguish between a cosmological origin or a solar system origin (such as a dim, diffuse, spherical cloud of cometary dust).
Publisher: Springer International Publishing
Date: 2016
Publisher: Oxford University Press (OUP)
Date: 03-12-2015
Publisher: Cambridge University Press (CUP)
Date: 08-2012
DOI: 10.1017/S1743921313004523
Abstract: The Dark Energy Survey (DES) will be the new state-of the-art in large-scale galaxy imaging surveys. With 5,000 deg 2 , it will cover an area of the sky similar to SDSS-II, but will go over two magnitudes deeper, reaching 24 th magnitude in all four optical bands ( griz ). DES will further provide observations in the redder Y -band and will be complemented with VISTA observations in the near-infrared bands JHK . Hence DES will furnish an unprecedented combination of sky and wavelength coverage and depth, unreached by any of the existing galaxy surveys. The very nature of the DES data set – large volume at intermediate photometric depth – allows us to probe galaxy formation and evolution within a cosmic-time range of ~ 10 Gyr and in different environments. In fact there will be many galaxy clusters available for galaxy evolution studies, given that one of the main aims of DES is to use their abundance to constrain the equation of state of dark energy. The X-ray follow up of these clusters, coupled with the use of gravitational lensing, will provide very precise measures of their masses, enabling us to study in detail the influence of the environment on galaxy formation and evolution processes. DES will leverage the study of these processes by allowing us to perform a detailed investigation of the galaxy luminosity and stellar mass functions and of the relationship between dark and baryonic matter as described by the Halo Occupation Distribution.
Publisher: Oxford University Press (OUP)
Date: 05-06-2021
Abstract: The Deep Extragalactic VIsible Legacy Survey (DEVILS) is an ongoing high-completeness, deep spectroscopic survey of ∼60 000 galaxies to Y & 21.2 mag, over ∼6 deg2 in three well-studied deep extragalactic fields: D10 (COSMOS), D02 (XMMLSS), and D03 (ECDFS). Numerous DEVILS projects all require consistent, uniformly derived and state-of-the-art photometric data with which to measure galaxy properties. Existing photometric catalogues in these regions either use varied photometric measurement techniques for different facilities/wavelengths leading to inconsistencies, older imaging data and/or rely on source detection and photometry techniques with known problems. Here, we use the ProFound image analysis package and state-of-the-art imaging data sets (including Subaru-HSC, VST-VOICE, VISTA-VIDEO, and UltraVISTA-DR4) to derive matched-source photometry in 22 bands from the FUV to 500 $\\mu$m. This photometry is found to be consistent, or better, in colour analysis to previous approaches using fixed-size apertures (which are specifically tuned to derive colours), but produces superior total source photometry, essential for the derivation of stellar masses, star formation rates, star formation histories, etc. Our photometric catalogue is described in detail and, after internal DEVILS team projects, will be publicly released for use by the broader scientific community.
Publisher: American Astronomical Society
Date: 26-06-2019
Publisher: Oxford University Press (OUP)
Date: 21-04-2018
Publisher: Oxford University Press (OUP)
Date: 11-12-2017
Publisher: Oxford University Press (OUP)
Date: 16-09-2014
Publisher: Oxford University Press (OUP)
Date: 22-01-2018
DOI: 10.1093/MNRAS/STY124
Publisher: Oxford University Press (OUP)
Date: 10-2010
Publisher: Oxford University Press (OUP)
Date: 06-11-2017
Publisher: Oxford University Press (OUP)
Date: 30-04-2022
Abstract: We present a complete structural analysis of the ellipticals (E), diffuse bulges (dB), compact bulges (cB), and discs (D) within a redshift range 0 & z & 1, and stellar mass log10(M*/M⊙) ≥ 9.5 volume-limited s le drawn from the combined DEVILS and HST-COSMOS region. We use the profit code to profile over ∼35 000 galaxies for which visual classification into single or double component was pre-defined in Paper-I. Over this redshift range, we see a growth in the total stellar mass density (SMD) of a factor of 1.5. At all epochs we find that the dominant structure, contributing to the total SMD, is the disc, and holds a fairly constant share of $\\sim 60{{\\ \\rm per\\ cent}}$ of the total SMD from z = 0.8 to z = 0.2, dropping to $\\sim 30{{\\ \\rm per\\ cent}}$ at z = 0.0 (representing $\\sim 33{{\\ \\rm per\\ cent}}$ decline in the total disc SMD). Other classes (E, dB, and cB) show steady growth in their numbers and integrated stellar mass densities. By number, the most dramatic change across the full mass range is in the growth of diffuse bulges. In terms of total SMD, the biggest gain is an increase in massive elliptical systems, rising from 20 per cent at z = 0.8 to equal that of discs at z = 0.0 (30 per cent) representing an absolute mass growth of a factor of 2.5. Overall, we see a clear picture of the emergence and growth of all three classes of spheroids over the past 8 Gyr, and infer that in the later half of the Universe’s timeline spheroid-forming processes and pathways (secular evolution, mass-accretion, and mergers) appear to dominate mass transformation over quiescent disc growth.
Publisher: Oxford University Press (OUP)
Date: 18-09-2014
Publisher: Oxford University Press (OUP)
Date: 29-11-0001
Publisher: Oxford University Press (OUP)
Date: 05-06-2019
Publisher: Oxford University Press (OUP)
Date: 20-05-2014
DOI: 10.1093/MNRAS/STU727
Publisher: Oxford University Press (OUP)
Date: 08-07-2015
Publisher: Oxford University Press (OUP)
Date: 02-07-2013
Publisher: Oxford University Press (OUP)
Date: 03-12-2015
Publisher: Springer Singapore
Date: 07-12-2017
Publisher: Oxford University Press (OUP)
Date: 14-06-2018
Publisher: Oxford University Press (OUP)
Date: 16-01-2018
DOI: 10.1093/MNRAS/STY127
Publisher: EDP Sciences
Date: 10-2022
DOI: 10.1051/0004-6361/202243101
Abstract: Aims. The circumgalactic medium (CGM) plays an important role in galaxy evolution as the main interface between the star-forming body of galaxies and the surrounding cosmic network of in- and out-flowing matter. In this work, we aim to characterize the hot phase of the CGM in a large s le of galaxies using recent soft-X-ray observations made by SRG /eROSITA. Methods. We stack X-ray events from the ‘eROSITA Final Equatorial Depth Survey’ (eFEDS) around central galaxies in the 9hr field of the ‘GAlaxy and Mass Assembly’ (GAMA) survey to construct radially projected X-ray luminosity profiles in the 0.5–2 keV rest frame energy band as a function of their stellar mass and specific star formation rate. We consider s les of quiescent (star-forming) galaxies in the stellar mass range 2 × 10 10 –10 12 M ⊙ (3 × 10 9 –6 × 10 11 M ⊙ ). Results. For quiescent galaxies, the X-ray profiles are clearly extended throughout the available mass range however, the measured profile is likely biased high because of projection effects, as these galaxies tend to live in dense and hot environments. For the most massive star-forming s les (≥10 11 M ⊙ ), there is a hint of detection of extended emission. On the other hand, for star-forming galaxies with 10 11 M ⊙ the X-ray stacked profiles are compatible with unresolved sources and are consistent with the expected emission from faint active galactic nuclei (AGN) and X-ray binaries. We measure for the first time the mean relation between average X-ray luminosity and stellar mass separately for quiescent and star-forming galaxies. We find that the relation is different for the two galaxy populations: high-mass (≥10 11 M ⊙ ) star-forming or quiescent galaxies follow the expected scaling of virialized hot haloes, while lower mass star-forming galaxies show a less prominent luminosity and a weaker dependence on stellar mass consistent with empirical models of the population of weak AGN. When comparing our results with state-of-the-art numerical simulations (IllustrisTNG and EAGLE), we find overall consistency on the average emission on large ( 80 kpc) scales at masses ≥10 11 M ⊙ , but disagreement on the small scales, where brighter-than-observed compact cores are predicted. The simulations also do not predict the clear differentiation that we observe between quiescent and star-forming galaxies in our s les. Conclusions. This is a stepping stone towards a more profound understanding of the hot phase of the CGM, which holds a key role in the regulation of star formation. Future analysis using eROSITA all-sky survey data, combined with future generation galaxy evolution surveys, shall provide much enhanced quantitative measurements and mapping of the CGM and its hot phase(s).
Publisher: Oxford University Press (OUP)
Date: 09-01-2019
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.
Publisher: Oxford University Press (OUP)
Date: 10-10-2022
Abstract: We use two independent galaxy-formation simulations, flares, a cosmological hydrodynamical simulation, and shark, a semi-analytic model, to explore how well the JWST will be able to uncover the existence and parameters of the star-forming main sequence (SFS) at z = 5 → 10, i.e. shape, scatter, normalization. Using two independent simulations allows us to isolate predictions (e.g. stellar mass, star formation rate, SFR, luminosity functions) that are robust to or highly dependent on the implementation of the physics of galaxy formation. Both simulations predict that JWST can observe ≥70–90 per cent (for shark and flares, respectively) of galaxies up to z ∼ 10 (down to stellar masses of ${\\approx}10^{8.3}\\rm M_{\\odot }$ and SFRs of ${\\approx}10^{0.5}{\\rm M}_{\\odot }\\,{\\rm yr}^{-1}$) in modest integration times and given current proposed survey areas (e.g. the Web COSMOS 0.6 deg2) to accurately constrain the parameters of the SFS. Although both simulations predict qualitatively similar distributions of stellar mass and SFR. There are important quantitative differences, such as the abundance of massive, star-forming galaxies with flares predicting a higher abundance than shark the early onset of quenching as a result of black hole growth in flares (at z ≈ 8), not seen in shark until much lower redshifts and the implementation of synthetic photometry with flares predicting more JWST-detected galaxies (∼90 per cent) than shark (∼70 per cent) at z = 10. JWST observations will distinguish between these models, leading to a significant improvement upon our understanding of the formation of the very first galaxies.
Publisher: European Southern Observatory (ESO)
Date: 2019
Publisher: Oxford University Press (OUP)
Date: 11-09-2020
Abstract: We apply the spectral energy distribution (SED) fitting code ProSpect to multiwavelength imaging for ∼7000 galaxies from the GAMA survey at z & 0.06, in order to extract their star formation histories. We combine a parametric description of the star formation history with a closed-box evolution of metallicity where the present-day gas-phase metallicity of the galaxy is a free parameter. We show with this approach that we are able to recover the observationally determined cosmic star formation history (CSFH), an indication that stars are being formed in the correct epoch of the Universe, on average, for the manner in which we are conducting SED fitting. We also show the contribution to the CSFH of galaxies of different present-day visual morphologies and stellar masses. Our analysis suggests that half of the mass in present-day elliptical galaxies was in place 11 Gyr ago. In other morphological types, the stellar mass formed later, up to 6 Gyr ago for present-day irregular galaxies. Similarly, the most massive galaxies in our s le were shown to have formed half their stellar mass by 11 Gyr ago, whereas the least massive galaxies reached this stage as late as 4 Gyr ago (the well-known effect of ‘galaxy downsizing’). Finally, our metallicity approach allows us to follow the average evolution in gas-phase metallicity for populations of galaxies and extract the evolution of the cosmic metal mass density in stars and in gas, producing results in broad agreement with independent, higher redshift observations of metal densities in the Universe.
Publisher: American Astronomical Society
Date: 03-2022
Abstract: We measure how the atomic gas (H i ) fraction f H I = M H I M * of groups and pairs taken as single units vary with average stellar mass (〈 M * 〉) and average star formation rate (〈SFR〉), compared to isolated galaxies. The H i 21 cm emission observation are from (i) archival ALFALFA survey data covering three fields from the GAMA survey (provides environmental and galaxy properties), and (ii) DINGO pilot survey data of one of those fields. The mean f H i for different units (groups airs/isolated galaxies) are measured in regions of the log(〈 M * 〉)–log(〈SFR〉) plane, relative to the z ∼ 0 star-forming main sequence (SFMS) of in idual galaxies, by stacking f H i spectra of in idual units. For ALFALFA, f H i spectra of units are measured by extracting H i spectra over the full groups air areas and iding by the total stellar mass of member galaxies. For DINGO, f H i spectra of units are measured by co-adding H i spectra of in idual member galaxies, followed by ision by their total stellar mass. For all units, the mean f H i decreases as we move to higher 〈 M * 〉 along the SFMS and as we move from above the SFMS to below it at any 〈 M * 〉. From the DINGO-based study, mean f H i in groups appears to be lower compared to isolated galaxies for all 〈 M * 〉 along the SFMS. From the ALFALFA-based study, we find substantially higher mean f H i in groups compared to isolated galaxies (values for pairs being intermediate) for 〈 M * 〉 ≲ 10 9.5 M ⊙ , indicating the presence of substantial amounts of H i not associated with cataloged member galaxies in low mass groups.
Publisher: Oxford University Press (OUP)
Date: 09-03-2021
Abstract: Using high-resolution Hubble Space Telescope imaging data, we perform a visual morphological classification of ∼36 000 galaxies at z & 1 in the deep extragalactic visible legacy survey/cosmological evolution survey region. As the main goal of this study, we derive the stellar mass function (SMF) and stellar mass density (SMD) sub- ided by morphological types. We find that visual morphological classification using optical imaging is increasingly difficult at z & 1 as the fraction of irregular galaxies and merger systems (when observed at rest-frame UV/blue wavelengths) dramatically increases. We determine that roughly two-thirds of the total stellar mass of the Universe today was in place by z ∼ 1. Double-component galaxies dominate the SMD at all epochs and increase in their contribution to the stellar mass budget to the present day. Elliptical galaxies are the second most dominant morphological type and increase their SMD by ∼2.5 times, while by contrast, the pure-disc population significantly decreases by $\\sim 85{{\\ \\rm per\\ cent}}$. According to the evolution of both high- and low-mass ends of the SMF, we find that mergers and in situ evolution in discs are both present at z & 1, and conclude that double-component galaxies are predominantly being built by the in situ evolution in discs (apparent as the growth of the low-mass end with time), while mergers are likely responsible for the growth of ellipticals (apparent as the increase of intermediate/high-mass end).
Publisher: Oxford University Press (OUP)
Date: 02-2016
Publisher: Oxford University Press (OUP)
Date: 26-11-2021
Abstract: Here, we present a catalogue of blended spectra in Data Release 1 of the Deep Extragalactic VIsible Legacy Survey (DEVILS) on the Anglo-Australian Telescope. Of the 23 197 spectra, 181 showed signs of a blend of redshifts and spectral templates. We examine these blends in detail for signs of either a candidate strong lensing galaxy or a useful overlapping galaxy pair. One of the three DEVILS target fields, COSMOS (D10), is close to complete and it is fully imaged with Hubble Space Telescope Advanced Camera for Surveys, and we visually examine the 57 blended spectra in this field in the F814W postage st s. Nine are classical strong lensing candidates with an elliptical as the lens, out to higher redshifts than any previous search with spectroscopic surveys such as Sloan Digital Sky Survey (SDSS) or Galaxy And Mass Assembly. The gravitational lens candidate success rate is similar to earlier such searches (0.1 per cent). Strong gravitational lenses identified with blended spectroscopy have typically shown a high success rate (& per cent), which make these interesting targets for future higher resolution lensing studies, monitoring for supernova cosmography, or searches for magnified atomic hydrogen signal.
Publisher: Oxford University Press (OUP)
Date: 12-04-2016
DOI: 10.1093/MNRAS/STW832
Publisher: Oxford University Press (OUP)
Date: 20-12-2018
Publisher: EDP Sciences
Date: 03-2020
DOI: 10.1051/0004-6361/201937228
Abstract: Context. Several new multi-object spectrographs are currently planned or under construction that are capable of observing thousands of Galactic and extragalactic objects simultaneously. Aims. In this paper we present a probabilistic fibre-to-target assignment algorithm that takes spectrograph targeting constraints into account and is capable of dealing with multiple concurrent surveys. We present this algorithm using the 4-m Multi-Object Spectroscopic Telescope (4MOST) as an ex le. Methods. The key idea of the proposed algorithm is to assign probabilities to fibre-target pairs. The assignment of probabilities takes the fibre positioner’s capabilities and constraints into account. Additionally, these probabilities include requirements from surveys and take the required exposure time, number density variation, and angular clustering of targets across each survey into account. The main advantage of a probabilistic approach is that it allows for accurate and easy computation of the target selection function for the different surveys, which involves determining the probability of observing a target, given an input catalogue. Results. The probabilistic fibre-to-target assignment allows us to achieve maximally uniform completeness within a single field of view. The proposed algorithm maximises the fraction of successfully observed targets whilst minimising the selection bias as a function of exposure time. In the case of several concurrent surveys, the algorithm maximally satisfies the scientific requirements of each survey and no specific survey is penalised or prioritised. Conclusions. The algorithm presented is a proposed solution for the 4MOST project that allows for an unbiased targeting of many simultaneous surveys. With some modifications, the algorithm may also be applied to other multi-object spectroscopic surveys.
Publisher: Oxford University Press (OUP)
Date: 27-04-2023
Abstract: The time-scales on which galaxies move out of the blue cloud to the red sequence ($\\tau ^{}_\\mathrm{Q}$ ) provide insight into the mechanisms driving quenching. Here, we build upon previous work, where we showcased a method to reconstruct the colour evolution of observed low-redshift galaxies from the Galaxy And Mass Assembly (GAMA) survey based on spectral energy distribution (SED) fitting with ProSpect, together with a statistically driven definition for the blue and red populations. We also use the predicted colour evolution from the shark semi-analytic model, combined with SED fits of our simulated galaxy s le, to study the accuracy of the measured $\\tau ^{}_\\mathrm{Q}$ and gain physical insight into the colour evolution of galaxies. In this work, we measure $\\tau ^{}_\\mathrm{Q}$ in a consistent approach for both observations and simulations. After accounting for selection bias, we find evidence for an increase in $\\tau ^{}_\\mathrm{Q}$ in GAMA as a function of cosmic time (from $\\tau ^{}_\\mathrm{Q}$ ∼ 1 Gyr to $\\tau ^{}_\\mathrm{Q}$ ∼ 2 Gyr in the lapse of ∼4 Gyr), but not in shark ($\\tau ^{}_\\mathrm{Q}$ ≲ 1 Gyr). Our observations and simulations disagree on the effect of stellar mass, with GAMA showing massive galaxies transitioning faster, but is the opposite in shark. We find that environment only impacts galaxies below ∼1010 M⊙ in GAMA, with satellites having shorter $\\tau ^{}_\\mathrm{Q}$ than centrals by ∼0.4 Gyr, with shark only in qualitative agreement. Finally, we compare to previous literature, finding consistency with time-scales in the order of couple Gyr, but with several differences that we discuss.
Publisher: Oxford University Press (OUP)
Date: 06-07-2016
Publisher: Oxford University Press (OUP)
Date: 31-05-2017
Publisher: European Southern Observatory (ESO)
Date: 2019
Publisher: EDP Sciences
Date: 11-2018
DOI: 10.1051/0004-6361/201833785
Abstract: Context . Massive ultra-compact galaxies (MUGs) are common at z = 2−3, but very rare in the nearby Universe. Simulations predict that the few surviving MUGs should reside in galaxy clusters, whose large relative velocities prevent them from merging, thus maintaining their original properties (namely stellar populations, masses, sizes and dynamical state). Aims. Our goal is to obtain a complete census of the MUG population at 0.02 z 0.3, determining the number density, population properties and environment. Methods . We have taken advantage of the high-completeness, large-area spectroscopic GAMA survey, complementing it with deeper imaging from the KiDS and VIKING surveys. We find a set of 22 bona-fide MUGs, defined as having high stellar mass ( 8 × 10 10 M ⊙ ) and compact size ( R e 2 kpc). An additional set of seven lower-mass objects (6 × 10 10 M ⋆ / M ⊙ 8 × 10 10 ) are also potential candidates according to typical mass uncertainties. Results . The comoving number density of MUGs at low redshift ( z 0.3) is constrained at (1.0 ± 0.4)×10 −6 Mpc −3 , consistent with galaxy evolution models. However, we find a mixed distribution of old and young galaxies, with a quarter of the s le representing (old) relics. MUGs have a predominantly early or swollen disk morphology (Sérsic index 1 n 2.5) with high stellar surface densities (⟨Σ e ⟩∼10 10 M ⊙ Kpc −2 ). Interestingly, a large fraction feature close companions – at least in projection – suggesting that many (but not all) reside in the central regions of groups. Halo masses show these galaxies inhabit average-mass groups. Conclusions . As MUGs are found to be almost equally distributed among environments of different masses, their relative fraction is higher in more massive overdensities, matching the expectations that some of these galaxies fell in these regions at early times. However, there must be another channel leading some of these galaxies to an abnormally low merger history because our s le shows a number of objects that do not inhabit particularly dense environments.
Publisher: Oxford University Press (OUP)
Date: 18-06-2018
Publisher: Oxford University Press (OUP)
Date: 17-08-2010
Publisher: Oxford University Press (OUP)
Date: 27-02-2017
Publisher: American Astronomical Society
Date: 08-09-2016
Publisher: EDP Sciences
Date: 10-2018
DOI: 10.1051/0004-6361/201832697
Abstract: Aims : We aim to investigate if the environment (characterised by the host dark matter halo mass) plays any role in shaping the galaxy star formation main sequence (MS). Methods : The Galaxy and Mass Assembly project (GAMA) combines a spectroscopic survey with photometric information in 21 bands from the far-ultraviolet (FUV) to the far-infrared (FIR). Stellar masses and dust-corrected star-formation rates (SFR) are derived from spectral energy distribution (SED) modelling using MAGPHYS. We use the GAMA galaxy group catalogue to examine the variation of the fraction of star-forming galaxies (SFG) and properties of the MS with respect to the environment. Results : We examine the environmental dependence for stellar mass selected s les without preselecting star-forming galaxies and study any dependence on the host halo mass separately for centrals and satellites out to z ∼ 0.3. We find the SFR distribution at fixed stellar mass can be described by the combination of two Gaussians (referred to as the star-forming Gaussian and the quiescent Gaussian). Using the observed bimodality to define SFG, we investigate how the fraction of SFG F(SFG) and properties of the MS change with environment. For centrals, the position of the MS is similar to the field but with a larger scatter. No significant dependence on halo mass is observed. For satellites, the position of the MS is almost always lower (by ∼0.2 dex) compared to the field and the width is almost always larger. F(SFG) is similar between centrals (in different halo mass bins) and field galaxies. However, for satellites F(SFG) decreases with increasing halo mass and this dependence is stronger towards lower redshift.
Publisher: Oxford University Press (OUP)
Date: 05-05-2023
Abstract: Traditionally, the far-ultraviolet (FUV) to far-infrared (FIR) and radio spectral energy distributions (SEDs) of galaxies have been considered separately despite the common physical process shaping them. In this work, we explore the utility of simultaneously fitting FUV-radio SEDs using an extended version of the ProSpect SED fitting code considering contributions from both free–free and synchrotron emission. We use a small s le of galaxies from the Deep Extragalactic VIsible Legacy Survey (DEVILS) and the Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel (KINGFISH) where high-quality and robust FUV-radio data are available to provide an ideal s le for testing a radio extension of ProSpect. As the parametrization of the radio extension links the radio continuum to the FIR emission, we explore the benefit of using radio continuum measurements as a constraint on the energy balance between dust attenuation and emission. We find that for situations where mid-IR–FIR photometry is unavailable, including a 1.4 GHz continuum measurement allows for improved accuracy in recovered star formation rates and dust luminosities of galaxies reducing the median uncertainty by 0.1 and 0.2 dex, respectively. We also demonstrate that incorporating 3 and 10 GHz measurements allows for further constraint on the energy balance and therefore the star formation rate and dust luminosity. This demonstrates the advantage of extending FUV–FIR SED fitting techniques to radio frequencies, especially as we move into an era where FIR surveys will remain limited and radio data become abundant (i.e. with the SKA and precursors).
Publisher: Oxford University Press (OUP)
Date: 28-03-2016
DOI: 10.1093/MNRAS/STW722
Publisher: Oxford University Press (OUP)
Date: 16-03-2019
DOI: 10.1093/MNRAS/STZ799
Publisher: Oxford University Press (OUP)
Date: 22-09-2017
Publisher: Oxford University Press (OUP)
Date: 10-01-2015
Publisher: Oxford University Press (OUP)
Date: 21-09-2020
Abstract: How do galaxy properties (such as stellar mass, luminosity, star formation rate, and morphology) and their evolution depend on the mass of their host dark matter halo? Using the Galaxy and Mass Assembly group catalogue, we address this question by exploring the dependence on host halo mass of the luminosity function (LF) and stellar mass function (SMF) for grouped galaxies sub ided by colour, morphology, and central/satellite. We find that spheroidal galaxies in particular dominate the bright and massive ends of the LF and SMF, respectively. More massive haloes host more massive and more luminous central galaxies. The satellites LF and SMF, respectively, show a systematic brightening of characteristic magnitude, and increase in characteristic mass, with increasing halo mass. In contrast to some previous results, the faint-end and low-mass slopes show little systematic dependence on halo mass. Semi-analytic models and simulations show similar or enhanced dependence of central mass and luminosity on halo mass. Faint and low-mass simulated satellite galaxies are remarkably independent of halo mass, but the most massive satellites are more common in more massive groups. In the first investigation of low-redshift LF and SMF evolution in group environments, we find that the red/blue ratio of galaxies in groups has increased since redshift z ≈ 0.3 relative to the field population. This observation strongly suggests that quenching of star formation in galaxies as they are accreted into galaxy groups is a significant and ongoing process.
Publisher: EDP Sciences
Date: 12-2018
Publisher: Oxford University Press (OUP)
Date: 07-06-2016
Publisher: Oxford University Press (OUP)
Date: 16-02-2016
DOI: 10.1093/MNRAS/STW134
Publisher: Oxford University Press (OUP)
Date: 05-2010
Publisher: Oxford University Press (OUP)
Date: 27-07-2012
Publisher: Oxford University Press (OUP)
Date: 30-07-2016
Publisher: Oxford University Press (OUP)
Date: 19-02-2019
DOI: 10.1093/MNRAS/STZ485
Publisher: Oxford University Press (OUP)
Date: 11-05-2017
Publisher: Oxford University Press (OUP)
Date: 04-02-2022
Abstract: Mapping the evolution of galaxy colours, from blue star forming to red passive systems, is fundamental to understand the processes involved in galaxy evolution. To this end, we reconstruct the colour evolution of low-redshift galaxies, combining stellar templates with star formation and metallicity histories of galaxies from the Galaxy And Mass Assembly survey and shark semi-analytical model. We use these colour histories to robustly characterize the evolution of red and blue galaxy populations over cosmic time. Using a Gaussian Mixture Model to characterize the colour distribution at any given epoch and stellar mass, we find both observations and simulations strongly favour a model with only two populations (blue and red), with no evidence for a third ‘green’ population. We map the evolution of mean, weight, and scatter of the blue and red populations as a function of both stellar mass and lookback time. Using our simulated galaxy catalogue as a testbed, we find that we can accurately recover galaxies colour histories up to a lookback time of ∼6 Gyr. We find that both populations show little change in the mean colour for low-mass galaxies, while the colours at the massive end become significantly redder with time. The stellar mass above which the galaxy population is predominantly red decreases by 0.3 dex in the last 5 Gyrs. We find a good agreement between observations and simulations, with the largest tension being that massive galaxies from shark are too blue (a known issue with many galaxy evolution models).
Publisher: Oxford University Press (OUP)
Date: 19-06-2015
Publisher: Cambridge University Press (CUP)
Date: 2022
DOI: 10.1017/PASA.2022.4
Abstract: We present Hubble Space Telescope Wide Field Camera 3 photometric and grism observations of the candidate ultra-high-redshift ( $z $ ) radio galaxy, GLEAM J0917–0012. This radio source was selected due to the curvature in its 70–230 MHz, low-frequency Murchison Widefield Array radio spectrum and its faintness in K -band. Follow-up spectroscopic observations of this source with the Jansky Very Large Array and Atacama Large Millimetre Array were inconclusive as to its redshift. Our F105W and F0986M imaging observations detect the host of GLEAM J0917–0012 and a companion galaxy, $\\sim$ one arcsec away. The G102 grism observations reveal a single weak line in each of the spectra of the host and the companion. To help identify these lines we utilised several photometric redshift techniques including template fitting to the grism spectra, fitting the ultraviolet (UV)-to-radio photometry with galaxy templates plus a synchrotron model, fitting of the UV-to-near-infrared photometry with EAZY , and fitting the radio data alone with RAiSERed . For the host of GLEAM J0917–0012 we find a line at $1.12\\,\\mu$ m and the UV-to-radio spectral energy distribution (SED) fitting favours solutions at $z\\sim 2$ or $z\\sim 8$ . While this fitting shows a weak preference for the lower redshift solution, the models from the higher redshift solution are more consistent with the strength of the spectral line. The redshift constraint by RAiSERed of $ .5$ also supports the interpretation that this line could be Lyman $-\\alpha$ at $z=8.21$ however EAZY favours the $z\\sim 2$ solution. We discuss the implications of both solutions. For the companion galaxy we find a line at $0.98\\,\\mu$ m and the SED fitting favours solutions at $z $ implying that the line could be the [OII] $\\lambda3727$ doublet at $z=1.63$ (although the EAZY solution is $z\\sim 2.6\\pm 0.5$ ). Further observations are still required to unambiguously determine the redshift of this intriguing candidate ultra-high-redshift radio galaxy.
Publisher: American Astronomical Society
Date: 08-2022
Abstract: We present the first measurements of H i galaxy scaling relations from a blind survey at z 0.15. We perform spectral stacking of 9023 spectra of star-forming galaxies undetected in H i at 0.23 z 0.49, extracted from MIGHTEE-H i Early Science data cubes, acquired with the MeerKAT radio telescope. We stack galaxies in bins of galaxy properties (stellar mass M * , star formation rateSFR, and specific star formation rate sSFR, with sSFR ≡ M * /SFR), obtaining ≳5 σ detections in most cases, the strongest H i -stacking detections to date in this redshift range. With these detections, we are able to measure scaling relations in the probed redshift interval, finding evidence for a moderate evolution from the median redshift of our s le z med ∼ 0.37 to z ∼ 0. In particular, low- M * galaxies ( log 10 ( M * / M ⊙ ) ∼ 9 ) experience a strong H i depletion (∼0.5 dex in log 10 ( M H I / M ⊙ ) ), while massive galaxies ( log 10 ( M * / M ⊙ ) ∼ 11 ) keep their H i mass nearly unchanged. When looking at the star formation activity, highly star-forming galaxies evolve significantly in M H I ( f H I , where f H I ≡ M H I / M * ) at fixed SFR (sSFR), while at the lowest probed SFR (sSFR) the scaling relations show no evolution. These findings suggest a scenario in which low- M * galaxies have experienced a strong H i depletion during the last ∼5 Gyr, while massive galaxies have undergone a significant H i replenishment through some accretion mechanism, possibly minor mergers. Interestingly, our results are in good agreement with the predictions of the simba simulation. We conclude that this work sets novel important observational constraints on galaxy scaling relations.
Publisher: Oxford University Press (OUP)
Date: 03-11-2018
Publisher: Oxford University Press (OUP)
Date: 28-02-2017
DOI: 10.1093/MNRAS/STX503
Publisher: Oxford University Press (OUP)
Date: 09-11-2021
Abstract: We present the evolution of the star formation dispersion–stellar mass relation (σSFR–M⋆) in the DEVILS D10 region using new measurements derived using the ProSpect spectral energy distribution fitting code. We find that σSFR–M⋆ shows the characteristic ‘U-shape’ at intermediate stellar masses from 0.1 & z & 0.7 for a number of metrics, including using the deconvolved intrinsic dispersion. A physical interpretation of this relation is the combination of stochastic star formation and stellar feedback causing large scatter at low stellar masses and AGN feedback causing asymmetric scatter at high stellar masses. As such, the shape of this distribution and its evolution encodes detailed information about the astrophysical processes affecting star formation, feedback and the lifecycle of galaxies. We find that the stellar mass that the minimum σSFR occurs evolves linearly with redshift, moving to higher stellar masses with increasing lookback time and traces the turnover in the star-forming sequence. This minimum σSFR point is also found to occur at a fixed specific star formation rate (sSFR) at all epochs (sSFR ∼ 10−9.6 Gyr−1). The physical interpretation of this is that there exists a maximum sSFR at which galaxies can internally self-regulate on the tight sequence of star formation. At higher sSFRs, stochastic stellar processes begin to cause galaxies to be pushed both above and below the star-forming sequence leading to increased SFR dispersion. As the Universe evolves, a higher fraction of galaxies will drop below this sSFR threshold, causing the dispersion of the low stellar mass end of the star-forming sequence to decrease with time.
Publisher: Oxford University Press (OUP)
Date: 03-07-2023
Abstract: We use the Galaxy and Mass Assembly (GAMA) and the Deep Extragalactic Visible Legacy Survey (DEVILS) observational data sets to calculate the cosmic star formation rate (SFR) and active galactic nuclei (AGN) bolometric luminosity history (CSFH/CAGNH) over the last 12.5 billion years. SFRs and AGN bolometric luminosities were derived using the spectral energy distribution fitting code ProSpect, which includes an AGN prescription to self-consistently model the contribution from both AGN and stellar emission to the observed rest-frame ultra-violet to far-infrared photometry. We find that both the CSFH and CAGNH evolve similarly, rising in the early Universe up to a peak at look-back time ≈10 Gyr (z ≈ 2), before declining towards the present day. The key result of this work is that we find the ratio of CAGNH to CSFH has been flat ($\\approx 10^{42.5}\\, \\mathrm{erg \\, s^{-1}\\, {\\rm M}_{\\odot }^{-1}\\, yr}$) for 11 Gyr up to the present day, indicating that star formation and AGN activity have been coeval over this time period. We find that the stellar masses of the galaxies that contribute most to the CSFH and CAGNH are similar, implying a common cause, which is likely gas inflow. The depletion of the gas supply suppresses cosmic star formation and AGN activity equivalently to ensure that they have experienced similar declines over the last 10 Gyr. These results are an important milestone for reconciling the role of star formation and AGN activity in the life cycle of galaxies.
Publisher: American Astronomical Society
Date: 12-08-2016
Publisher: Oxford University Press (OUP)
Date: 23-02-2018
DOI: 10.1093/MNRAS/STY440
Publisher: Oxford University Press (OUP)
Date: 25-05-2017
Publisher: Oxford University Press (OUP)
Date: 07-06-2017
Publisher: Oxford University Press (OUP)
Date: 25-01-2014
Publisher: Oxford University Press (OUP)
Date: 23-06-2018
Publisher: Oxford University Press (OUP)
Date: 11-10-2010
Publisher: Oxford University Press (OUP)
Date: 19-11-2014
Publisher: Oxford University Press (OUP)
Date: 12-09-2016
Publisher: Oxford University Press (OUP)
Date: 30-11-2023
Publisher: American Astronomical Society
Date: 03-10-2008
DOI: 10.1086/593061
Publisher: Oxford University Press (OUP)
Date: 09-04-2020
Abstract: We present early science results from the First Large Absorption Survey in H i (FLASH), a spectroscopically blind survey for 21-cm absorption lines in cold hydrogen (H i) gas at cosmological distances using the Australian Square Kilometre Array Pathfinder (ASKAP). We have searched for H i absorption towards 1253 radio sources in the GAMA 23 field, covering redshifts between z = 0.34 and 0.79 over a sky area of approximately 50 deg2. In a purely blind search, we did not obtain any detections of 21-cm absorbers above our reliability threshold. Assuming a fiducial value for the H i spin temperature of Tspin = 100 K and source covering fraction cf = 1, the total comoving absorption path-length sensitive to all D ed Lyman α Absorbers (DLAs NH i ≥ 2 × 1020 cm−2) is ΔX = 6.6 ± 0.3 (Δz = 3.7 ± 0.2) and super-DLAs (NH i ≥ 2 × 1021 cm−2) is ΔX = 111 ± 6 (Δz= 63 ± 3). We estimate upper limits on the H i column density frequency distribution function that are consistent with measurements from prior surveys for redshifted optical DLAs, and nearby 21-cm emission and absorption. By cross-matching our s le of radio sources with optical spectroscopic identifications of galaxies in the GAMA 23 field, we were able to detect 21-cm absorption at z = 0.3562 towards NVSS J224500−343030, with a column density of $N_{\\rm H\\,\\small{I}} = (1.2 \\pm 0.1) \\times 10^{20}\\, (T_{\\rm spin}/100\\, \\mathrm{K})$ cm−2. The absorber is associated with GAMA J22450.05−343031.7, a massive early-type galaxy at an impact parameter of 17 kpc with respect to the radio source and which may contain a massive (MH i ≳ 3 × 109 M⊙) gas disc. Such gas-rich early types are rare, but have been detected in the nearby Universe.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2018
End Date: 11-2022
Summary: The influence of the dark-matter halo on galaxy evolution. This project aims to map the growth of the integrated stellar mass within galaxy structures over all time, and to explore the link between component growth and the mass of the dark matter halo. The project expects to provide a clear empirical record of galaxy growth, and a statement as to whether the changes seen are consistent with the predictions of numerical simulations.
Funder: Australian Research Council
View Funded Activity