scholarly journals Galaxy and mass assembly: luminosity and stellar mass functions in GAMA groups

2020 ◽  
Vol 499 (1) ◽  
pp. 631-652
Author(s):  
J A Vázquez-Mata ◽  
J Loveday ◽  
S D Riggs ◽  
I K Baldry ◽  
L J M Davies ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Mass Function ◽  
Stellar Mass ◽  
Dark Matter Halo ◽  
Central Mass ◽  
The Galaxy ◽  
Star Formation In Galaxies ◽  
Low Mass ◽  
Mass Assembly

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 subdivided 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.

scholarly journals Cosmological simulations of low-mass galaxies: some potential issues

2010 ◽  
Vol 6 (S270) ◽  
pp. 503-506
Author(s):  
Pedro Colín ◽  
Vladimir Avila-Reese ◽  
Octavio Valenzuela
Keyword(s):  
Star Formation ◽  
Adaptive Mesh Refinement ◽  
Mass Fraction ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Mesh Refinement ◽  
Adaptive Mesh ◽  
Stellar Mass ◽  
The Galaxy ◽  
Low Mass

AbstractCosmological Adaptive Mesh Refinement simulations are used to study the specific star formation rate (sSFR=SSF/Ms) history and the stellar mass fraction, fs=Ms/MT, of small galaxies, total masses MT between few × 1010 M⊙ to few ×1011 M⊙. Our results are compared with recent observational inferences that show the so-called “downsizing in sSFR” phenomenon: the less massive the galaxy, the higher on average is its sSFR, a trend seen at least since z ~ 1. The simulations are not able to reproduce this phenomenon, in particular the high inferred values of sSFR, as well as the low values of fs constrained from observations. The effects of resolution and sub-grid physics on the SFR and fs of galaxies are discussed.

scholarly journals A systematic search for galaxy proto-cluster cores at z ∼ 2

2020 ◽  
Vol 496 (3) ◽  
pp. 3169-3181
Author(s):  
Makoto Ando ◽  
Kazuhiro Shimasaku ◽  
Rieko Momose
Keyword(s):  
Galaxy Formation ◽  
Mass Range ◽  
Mass Function ◽  
Stellar Mass ◽  
Dark Matter Halo ◽  
Massive Galaxies ◽  
Quenching Efficiency ◽  
The Galaxy ◽  
Mass Assembly ◽  
Cluster Cores

ABSTRACT A proto-cluster core is the most massive dark matter halo (DMH) in a given proto-cluster. To reveal the galaxy formation in core regions, we search for proto-cluster cores at z ∼ 2 in ${\sim}1.5\, \mathrm{deg}^{2}$ of the COSMOS field. Using pairs of massive galaxies [log (M*/M⊙) ≥ 11] as tracers of cores, we find 75 candidate cores, among which 54 per cent are estimated to be real. A clustering analysis finds that these cores have an average DMH mass of $2.6_{-0.8}^{+0.9}\times 10^{13}\, \mathrm{M}_{\odot }$, or $4.0_{-1.5}^{+1.8}\, \times 10^{13} \, \mathrm{M}_{\odot }$ after contamination correction. The extended Press–Schechter model shows that their descendant mass at z = 0 is consistent with Fornax-like or Virgo-like clusters. Moreover, using the IllustrisTNG simulation, we confirm that pairs of massive galaxies are good tracers of DMHs massive enough to be regarded as proto-cluster cores. We then derive the stellar mass function (SMF) and the quiescent fraction for member galaxies of the 75 candidate cores. We find that the core galaxies have a more top-heavy SMF than field galaxies at the same redshift, showing an excess at log (M*/M⊙) ≳ 10.5. The quiescent fraction, $0.17_{-0.04}^{+0.04}$ in the mass range 9.0 ≤ log (M*/M⊙) ≤ 11.0, is about three times higher than that of field counterparts, giving an environmental quenching efficiency of $0.13_{-0.04}^{+0.04}$. These results suggest that stellar mass assembly and quenching are accelerated as early as z ∼ 2 in proto-cluster cores.

scholarly journals A contribution of star-forming clumps and accreting satellites to the mass assembly of z ∼ 2 galaxies

2019 ◽  
Vol 489 (2) ◽  
pp. 2792-2818 ◽  
Author(s):  
A Zanella ◽  
E Le Floc’h ◽  
C M Harrison ◽  
E Daddi ◽  
E Bernhard ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Mass ◽  
Mass Ratio ◽  
Star Forming ◽  
Spatially Resolved ◽  
The Galaxy ◽  
Mass Assembly

ABSTRACT We investigate the contribution of clumps and satellites to the galaxy mass assembly. We analysed spatially resolved HubbleSpace Telescope observations (imaging and slitless spectroscopy) of 53 star-forming galaxies at z ∼ 1–3. We created continuum and emission line maps and pinpointed residual ‘blobs’ detected after subtracting the galaxy disc. Those were separated into compact (unresolved) and extended (resolved) components. Extended components have sizes ∼2 kpc and comparable stellar mass and age as the galaxy discs, whereas the compact components are 1.5 dex less massive and 0.4 dex younger than the discs. Furthermore, the extended blobs are typically found at larger distances from the galaxy barycentre than the compact ones. Prompted by these observations and by the comparison with simulations, we suggest that compact blobs are in situ formed clumps, whereas the extended ones are accreting satellites. Clumps and satellites enclose, respectively, ∼20 per cent and ≲80 per cent of the galaxy stellar mass, ∼30 per cent and ∼20 per cent of its star formation rate. Considering the compact blobs, we statistically estimated that massive clumps (M⋆ ≳ 109 M⊙) have lifetimes of ∼650 Myr, and the less massive ones (108 < M⋆ < 109 M⊙) of ∼145 Myr. This supports simulations predicting long-lived clumps (lifetime ≳ 100 Myr). Finally, ≲30 per cent (13 per cent) of our sample galaxies are undergoing single (multiple) merger(s), they have a projected separation ≲10 kpc, and the typical mass ratio of our satellites is 1:5 (but ranges between 1:10 and 1:1), in agreement with literature results for close pair galaxies.

scholarly journals EDGE: the mass–metallicity relation as a critical test of galaxy formation physics

2019 ◽  
Vol 491 (2) ◽  
pp. 1656-1672 ◽  
Author(s):  
Oscar Agertz ◽  
Andrew Pontzen ◽  
Justin I Read ◽  
Martin P Rey ◽  
Matthew Orkney ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Dwarf Galaxy ◽  
Self Regulation ◽  
Stellar Mass ◽  
Dark Matter Halo ◽  
V Band ◽  
The Galaxy ◽  
Unique Constraint ◽  
Low Mass

ABSTRACT We introduce the ‘Engineering Dwarfs at Galaxy Formation’s Edge’ (EDGE) project to study the cosmological formation and evolution of the smallest galaxies in the Universe. In this first paper, we explore the effects of resolution and sub-grid physics on a single low-mass halo ($M_{\rm halo}=10^{9}{\, \rm M}_\odot$), simulated to redshift z = 0 at a mass and spatial resolution of $\sim 20{\, \rm M}_\odot$ and ∼3 pc. We consider different star formation prescriptions, supernova feedback strengths, and on-the-fly radiative transfer (RT). We show that RT changes the mode of galactic self-regulation at this halo mass, suppressing star formation by causing the interstellar and circumgalactic gas to remain predominantly warm (∼104 K) even before cosmic reionization. By contrast, without RT, star formation regulation occurs only through starbursts and their associated vigorous galactic outflows. In spite of this difference, the entire simulation suite (with the exception of models without any feedback) matches observed dwarf galaxy sizes, velocity dispersions, V-band magnitudes, and dynamical mass-to-light-ratios. This is because such structural scaling relations are predominantly set by the host dark matter halo, with the remaining model-to-model variation being smaller than the observational scatter. We find that only the stellar mass–metallicity relation differentiates the galaxy formation models. Explosive feedback ejects more metals from the dwarf, leading to a lower metallicity at a fixed stellar mass. We conclude that the stellar mass–metallicity relation of the very smallest galaxies provides a unique constraint on galaxy formation physics.

scholarly journals A systematic search for galaxy proto-cluster cores at z ∼ 2

2019 ◽  
Vol 15 (S359) ◽  
pp. 166-167
Author(s):  
Makoto Ando ◽  
Kazuhiro Shimasaku ◽  
Rieko Momose
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Clustering Analysis ◽  
Mass Function ◽  
Stellar Mass ◽  
Dark Matter Halo ◽  
Massive Galaxies ◽  
The Galaxy ◽  
Mass Assembly ◽  
Cluster Cores

AbstractA proto-cluster core is the most massive dark matter halo (DMH) in a given proto-cluster. To reveal the galaxy formation in core regions, we search for proto-cluster cores at z ˜ 2 in ˜1.5deg2 of the COSMOS field. Using pairs of massive galaxies (log (M*/Mʘ) ≥ 11) as tracers of cores, we find 75 candidate cores. A clustering analysis and the extended Press-Schechter model show that their descendant mass at z = 0 is consistent with Fornax-like or Virgo-like clusters. Moreover, using the IllustrisTNG simulation, we confirm that pairs of massive galaxies are good tracers of DMHs massive enough to be regarded as proto-cluster cores. We then derive the stellar mass function and the quiescent fraction for member galaxies of the 75 candidate cores. We find that stellar mass assembly and quenching are accelerated as early as z ˜ 2 in proto-cluster cores.

scholarly journals How feedback shapes galaxies: an analytic model

2019 ◽  
Vol 491 (4) ◽  
pp. 5083-5100
Author(s):  
Jaime Salcido ◽  
Richard G Bower ◽  
Tom Theuns
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Mass Function ◽  
Stellar Mass ◽  
Mass Relation ◽  
Analytic Model ◽  
The Galaxy ◽  
Formation Efficiency

ABSTRACT We introduce a simple analytic model of galaxy formation that links the growth of dark matter haloes in a cosmological background to the build-up of stellar mass within them. The model aims to identify the physical processes that drive the galaxy-halo co-evolution through cosmic time. The model restricts the role of baryonic astrophysics to setting the relation between galaxies and their haloes. Using this approach, galaxy properties can be directly predicted from the growth of their host dark matter haloes. We explore models in which the effective star formation efficiency within haloes is a function of mass (or virial temperature) and independent of time. Despite its simplicity, the model reproduces self-consistently the shape and evolution of the cosmic star formation rate density, the specific star formation rate of galaxies, and the galaxy stellar mass function, both at the present time and at high redshifts. By systematically varying the effective star formation efficiency in the model, we explore the emergence of the characteristic shape of the galaxy stellar mass function. The origin of the observed double Schechter function at low redshifts is naturally explained by two efficiency regimes in the stellar to halo mass relation, namely, a stellar feedback regulated stage, and a supermassive black hole regulated stage. By providing a set of analytic differential equations, the model can be easily extended and inverted, allowing the roles and impact of astrophysics and cosmology to be explored and understood.

scholarly journals The Iκεα model of feedback-regulated galaxy formation

2019 ◽  
Author(s):  
Mahavir Sharma ◽  
Tom Theuns
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Self Regulation ◽  
Mass Function ◽  
Stellar Mass ◽  
Gas Content ◽  
Dark Matter Halo ◽  
Star Forming

Abstract We present the Iκεα model of galaxy formation, in which a galaxy’s star formation rate is set by the balance between energy injected by feedback from massive stars and energy lost by the deepening of the potential of its host dark matter halo due to cosmological accretion. Such a balance is secularly stable provided that the star formation rate increases with the pressure in the star forming gas. The Iκεα model has four parameters that together control the feedback from star formation and the cosmological accretion rate onto a halo. Iκεα reproduces accurately the star formation rate as a function of halo mass and redshift in the eagle hydrodynamical simulation, even when all four parameters are held constant. It predicts the emergence of a star forming main sequence along which the specific star formation rate depends weakly on stellar mass with an amplitude that increases rapidly with redshift. We briefly discuss the emerging mass-metallicity relation, the evolution of the galaxy stellar mass function, and an extension of the model that includes feedback from active galactic nuclei (AGN). These self-regulation results are independent of the star formation law and the galaxy’s gas content. Instead, star forming galaxies are shaped by the balance between stellar feedback and cosmological accretion, with accurately accounting for energy losses associated with feedback a crucial ingredient.

scholarly journals Galaxy and Mass Assembly (GAMA): The environmental dependence of the galaxy main sequence

2018 ◽  
Vol 618 ◽  
pp. A1 ◽  
Author(s):  
L. Wang ◽  
P. Norberg ◽  
S. Brough ◽  
M. J. I. Brown ◽  
E. da Cunha ◽  
...  
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Spectral Energy Distribution ◽  
Stellar Mass ◽  
Dark Matter Halo ◽  
Spectral Energy ◽  
Star Forming ◽  
The Galaxy ◽  
Mass Assembly ◽  
Environmental Dependence

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 samples 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.

scholarly journals How robustly can we constrain the low-mass end of the z ∼ 6−7 stellar mass function? The limits of lensing models and stellar population assumptions in the Hubble Frontier Fields

2020 ◽  
Vol 501 (2) ◽  
pp. 1568-1590
Author(s):  
Lukas J Furtak ◽  
Hakim Atek ◽  
Matthew D Lehnert ◽  
Jacopo Chevallard ◽  
Stéphane Charlot
Keyword(s):  
Star Formation ◽  
Mass Function ◽  
Stellar Mass ◽  
Star Formation History ◽  
Space Telescope ◽  
Formation History ◽  
Low Mass ◽  
Stellar Masses ◽  
Dust Attenuation ◽  
The Impact

ABSTRACT We present new measurements of the very low mass end of the galaxy stellar mass function (GSMF) at z ∼ 6−7 computed from a rest-frame ultraviolet selected sample of dropout galaxies. These galaxies lie behind the six Hubble Frontier Field clusters and are all gravitationally magnified. Using deep Spitzer/IRAC and Hubble Space Telescope imaging, we derive stellar masses by fitting galaxy spectral energy distributions and explore the impact of different model assumptions and parameter degeneracies on the resulting GSMF. Our sample probes stellar masses down to $M_{\star }\gt 10^{6}\, \text{M}_{\odot}$ and we find the z ∼ 6−7 GSMF to be best parametrized by a modified Schechter function that allows for a turnover at very low masses. Using a Monte Carlo Markov chain analysis of the GSMF, including accurate treatment of lensing uncertainties, we obtain a relatively steep low-mass end slope $\alpha \simeq -1.96_{-0.08}^{+0.09}$ and a turnover at $\log (M_T/\text{M}_{\odot})\simeq 7.10_{-0.56}^{+0.17}$ with a curvature of $\beta \simeq 1.00_{-0.73}^{+0.87}$ for our minimum assumption model with constant star formation history (SFH) and low dust attenuation, AV ≤ 0.2. We find that the z ∼ 6−7 GSMF, in particular its very low mass end, is significantly affected by the assumed functional form of the star formation history and the degeneracy between stellar mass and dust attenuation. For example, the low-mass end slope ranges from $\alpha \simeq -1.82_{-0.07}^{+0.08}$ for an exponentially rising SFH to $\alpha \simeq -2.34_{-0.10}^{+0.11}$ when allowing AV of up to 3.25. Future observations at longer wavelengths and higher angular resolution with the James Webb Space Telescope are required to break these degeneracies and to robustly constrain the stellar mass of galaxies on the extreme low-mass end of the GSMF.

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