We build on a recent photometric decomposition analysis of 7506 Galaxy and Mass Assembly (GAMA) survey galaxies to derive stellar mass function fits to individual spheroid and disc component ...populations down to a lower mass limit of log(M
*/M⊙) = 8. We find that the spheroid/disc mass distributions for individual galaxy morphological types are well described by single Schechter function forms. We derive estimates of the total stellar mass densities in spheroids (ρspheroid = 1.24 ± 0.49 × 108 M⊙ Mpc −3h0.7) and discs (ρdisc = 1.20 ± 0.45 × 108 M⊙ Mpc −3h0.7), which translates to approximately 50 per cent of the local stellar mass density in spheroids and 48 per cent in discs. The remaining stellar mass is found in the dwarf ‘little blue spheroid’ class, which is not obviously similar in structure to either classical spheroid or disc populations. We also examine the variation of component mass ratios across galaxy mass and group halo mass regimes, finding the transition from spheroid to disc mass dominance occurs near galaxy stellar mass ∼1011 M⊙ and group halo mass ∼1012.5 M⊙
h
−1. We further quantify the variation in spheroid-to-total mass ratio with group halo mass for central and satellite populations as well as the radial variation of this ratio within groups.
ABSTRACT
We present catalogues of stellar masses, star formation rates (SFRs), and ancillary stellar population parameters for galaxies spanning 0 < z < 9 from the Deep Extragalactic VIsible Legacy ...Survey (DEVILS). DEVILS is a deep spectroscopic redshift survey with very high completeness, covering several premier deep fields including COSMOS (D10). Our stellar mass and SFR estimates are self-consistently derived using the spectral energy distribution (SED) modelling code ProSpect, using well-motivated parametrizations for dust attenuation, star formation histories, and metallicity evolution. We show how these improvements, and especially our physically motivated assumptions about metallicity evolution, have an appreciable systematic effect on the inferred stellar masses, at the level of ∼0.2 dex. To illustrate the scientific value of these data, we map the evolving galaxy stellar mass function (SMF) and the SFR–M⋆ relation for 0 < z < 4.25. In agreement with past studies, we find that most of the evolution in the SMF is driven by the characteristic density parameter, with little evolution in the characteristic mass and low-mass slopes. Where the SFR–M⋆ relation is indistinguishable from a power law at z > 2.6, we see evidence of a bend in the relation at low redshifts (z < 0.45). This suggests evolution in both the normalization and shape of the SFR–M⋆ relation since cosmic noon. It is significant that we only clearly see this bend when combining our new DEVILS measurements with consistently derived values for lower redshift galaxies from the Galaxy And Mass Assembly (GAMA) survey: this shows the power of having consistent treatment for galaxies at all redshifts.
Abstract
We derive new empirical scaling relations between Wide-field Infrared Survey Explorer (WISE) mid-IR (MIR) galaxy photometry and well-determined stellar masses from spectral energy ...distribution modeling of a suite of optical–infrared photometry provided by the Data Release 4 (DR4) Catalog of the GAMA-KiDS-VIKING survey of the southern G23 field. The MIR source extraction and characterization are drawn from the WISE Extended Source Catalogue and the archival ALLWISE catalog, combining both resolved and compact galaxies in the G23 sample to a redshift of 0.15. Three scaling relations are derived: W1 3.4
μ
m luminosity versus stellar mass, and WISE W1–W2, W1–W3 colors versus mass-to-light ratio (
M
/
L
, sensitive to a variety of galaxy types from passive to star-forming). For each galaxy in the sample, we then derive the combined stellar mass from these scaling relations, producing
M
⋆
estimates with better than ∼25%–30% accuracy for galaxies with >10
9
M
⊙
and <40%–50% for lower-luminosity dwarf galaxies. We also provide simple prescriptions for rest-frame corrections and estimating stellar masses using only the W1 flux and the W1–W2 color, making stellar masses more accessible to users of the WISE data. Given a redshift or distance, these new scaling relations will enable stellar mass estimates for any galaxy in the sky detected by WISE with high fidelity across a range of
M
/
L
ratios.
We measure the projected two-point correlation function of galaxies in the 180 deg2 equatorial regions of the GAMA II survey, for four different redshift slices between z = 0.0 and 0.5. To do this, ...we further develop the Cole method of producing suitable random catalogues for the calculation of correlation functions. We find that more r-band luminous, more massive and redder galaxies are more clustered. We also find that red galaxies have stronger clustering on scales less than ~3 h... Mpc. We compare to two different versions of the galform galaxy formation model, Lacey et al. (in preparation) and Gonzalez-Perez et al., and find that the models reproduce the trend of stronger clustering for more massive galaxies. However, the models underpredict the clustering of blue galaxies, can incorrectly predict the correlation function on small scales and underpredict the clustering in our sample of galaxies with $...\sim ... 3 L_...r... angle $. We suggest possible avenues to explore to improve these clustering predictions. The measurements presented in this paper can be used to test other galaxy formation models, and we make the measurements available online to facilitate this. (ProQuest: ... denotes formulae/symbols omitted.)
ABSTRACT
We present the new ProFuse r package, a simultaneous spectral (ultraviolet to far-infrared) and spatial structural decomposition tool that produces physical models of galaxies and their ...components. This combines the functionality of the recently released ProFound (for automatic source extraction), ProFit (for extended source profiling), and ProSpect (for stellar population modelling) software packages. The key novelty of ProFuse is that it generates images using a self-consistent model for the star formation and metallicity history of the bulge and disc separately, and uses target images across a range of wavelengths to define the model likelihood and optimize our physical galaxy reconstruction. The first part of the paper explores the ProFuse approach in detail, and compares results to published structural and stellar population properties. The latter part of the paper applies ProFuse to 6664 z < 0.06 GAMA galaxies. Using re-processed ugriZYJHKs imaging we extract structural and stellar population properties for bulges and discs in parallel. As well as producing true stellar mass based mass–size relationships, we further extend this correlation to explore the third dimensions of age and gas phase metallicity. The discs in particular demonstrate strong co-dependency between mass–size–age in a well-defined plane, where at a given disc stellar mass younger discs tend to be larger. These findings are in broad agreement with work at higher redshift, suggesting discs that formed earlier are physically smaller.
ABSTRACT
We utilize the galaxy shape catalogue from the first-year data release of the Subaru Hyper Suprime-Cam (HSC) survey to study the dark matter content of galaxy groups in the Universe using ...weak lensing. We use galaxy groups from the Galaxy Mass and Assembly galaxy survey in approximately 100 sq. degrees of the sky that overlap with the HSC survey as lenses. We restrict our analysis to the 1587 groups with at least five members. We divide these groups into six bins each of group luminosity and group member velocity dispersion and measure the lensing signal with a signal-to-noise ratio of 55 and 51 for these two different selections, respectively. We use a Bayesian halo model framework to infer the halo mass distribution of our groups binned in the two different observable properties and constrain the power-law scaling relation and the scatter between mean halo masses and the two-group observable properties. We obtain a 5 per cent constraint on the amplitude of the scaling relation between halo mass and group luminosity with 〈M〉 = (0.81 ± 0.04) × 1014 h−1 M⊙ for Lgrp = 1011.5 h−2 L⊙, and a power-law index of α = 1.01 ± 0.07. We constrain the amplitude of the scaling relation between halo mass and velocity dispersion to be 〈M〉 = (0.93 ± 0.05) × 1014 h−1 M⊙ for $\sigma = 500\, {\rm km\, s}^{-1}$ and a power-law index to be α = 1.52 ± 0.10. However, these scaling relations are sensitive to the exact cuts applied to the number of group members. Comparisons with similar scaling relations from the literature show that our results are consistent and have significantly reduced errors.
We investigate the relationship between colour and structure within galaxies using a large, volume-limited sample of bright, low-redshift galaxies with optical–near-infrared imaging from the Galaxy ...And Mass Assembly survey. We fit single-component, wavelength-dependent, elliptical Sérsic models to all passbands simultaneously, using software developed by the MegaMorph project. Dividing our sample by n and colour, the recovered wavelength variations in effective radius (R
e) and Sérsic index (n) reveal the internal structure, and hence formation history, of different types of galaxies. All these trends depend on n; some have an additional dependence on galaxy colour. Late-type galaxies (n
r
< 2.5) show a dramatic increase in Sérsic index with wavelength. This might be a result of their two-component (bulge–disc) nature, though stellar population gradients within each component and dust attenuation are likely to play a role. All galaxies show a substantial decrease in R
e with wavelength. This is strongest for early types (n
r
> 2.5), even though they maintain constant n with wavelength, revealing that ellipticals are a superimposition of different stellar populations associated with multiple collapse and merging events. Processes leading to structures with larger R
e must be associated with lower metallicity or younger stellar populations. This appears to rule out the formation of young cores through dissipative gas accretion as an important mechanism in the recent lives of luminous elliptical galaxies.
We describe the spectroscopic target selection for the Galaxy And Mass Assembly (GAMA) survey. The input catalogue is drawn from the Sloan Digital Sky Survey (SDSS) and UKIRT Infrared Deep Sky Survey ...(UKIDSS). The initial aim is to measure redshifts for galaxies in three 4°× 12° regions at 9, 12 and 14.5 h, on the celestial equator, with magnitude selections r < 19.4, z < 18.2 and KAB < 17.6 over all three regions, and r < 19.8 in the 12-h region. The target density is 1080 deg−2 in the 12-h region and 720 deg−2 in the other regions. The average GAMA target density and area are compared with completed and ongoing galaxy redshift surveys. The GAMA survey implements a highly complete star–galaxy separation that jointly uses an intensity-profile separator (Δsg=rpsf−rmodel as per the SDSS) and a colour separator. The colour separator is defined as Δsg,jk=J−K−f(g−i), where f(g−i) is a quadratic fit to the J−K colour of the stellar locus over the range 0.3 < g−i < 2.3. All galaxy populations investigated are well separated with Δsg,jk > 0.2. From 2 yr out of a 3-yr AAOmega program on the Anglo-Australian Telescope, we have obtained 79 599 unique galaxy redshifts. Previously known redshifts in the GAMA region bring the total up to 98 497. The median galaxy redshift is 0.2 with 99 per cent at z < 0.5. We present some of the global statistical properties of the survey, including K-band galaxy counts, colour–redshift relations and preliminary n(z).
We present a maximum-likelihood weak-lensing analysis of the mass distribution in optically selected spectroscopic Galaxy Groups (...) in the Galaxy And Mass Assembly (GAMA) survey, using background ...Sloan Digital Sky Survey (SDSS) photometric galaxies. The scaling of halo mass, ..., with various group observables is investigated. Our main results are as follows. (1) The measured relations of halo mass with group luminosity, virial volume and central galaxy stellar mass, M*, agree very well with predictions from mock group catalogues constructed from a GALFORM semi-analytical galaxy formation model implemented in the Millennium ...CDM N-body simulation. (2) The measured relations of halo mass with velocity dispersion and projected half-abundance radius show weak tension with mock predictions, hinting at problems in the mock galaxy dynamics and their small-scale distribution. (3) The median ... measured from weak lensing depends more sensitively on the lognormal dispersion in M* at fixed ... than it does on the median ... Our measurements suggest an intrinsic dispersion of ... Comparing our mass estimates with those in the catalogue, we find that the ... mass can give biased results when used to select subsets of the group sample. Of the various new halo-mass estimators that we calibrate using our weak-lensing measurements, group luminosity is the best single-proxy estimator of group mass. (ProQuest: ... denotes formulae/symbols omitted.)
We present the first application of a 'multiple-tracer' redshift-space distortion (RSD) analysis to an observational galaxy sample, using data from the Galaxy and Mass Assembly (GAMA) survey. Our ...data set is an r < 19.8 magnitude-limited sample of 178 579 galaxies covering the redshift interval z < 0.5 and area 180 deg2. We obtain improvements of 10-20 per cent in measurements of the gravitational growth rate compared to a single-tracer analysis, deriving from the correlated sample variance imprinted in the distributions of the overlapping galaxy populations. We present new expressions for the covariances between the auto-power and cross-power spectra of galaxy samples that are valid for a general survey selection function and weighting scheme. We find no evidence for a systematic dependence of the measured growth rate on the galaxy tracer used, justifying the RSD modelling assumptions, and validate our results using mock catalogues from N-body simulations. For multiple tracers selected by galaxy colour, we measure normalized growth rates in two independent redshift bins f...8(z = 0.18) = 0.36 ± 0.09 and f...8(z = 0.38) = 0.44 ± 0.06, in agreement with standard GR gravity and other galaxy surveys at similar redshifts. (ProQuest: ... denotes formulae/symbols omitted.)
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