ABSTRACT
The presence of massive galaxies at high z as recently observed by JWST appears to contradict the current ΛCDM cosmology. Here, we aim to alleviate this tension by incorporating ...uncertainties from three sources in counting galaxies: cosmic variance, error in stellar mass estimation, and backsplash enhancement. Each of these factors significantly increases the cumulative stellar mass density ρ*(>M*) at the high-mass end, and their combined effect can boost the density by more than one order of magnitude. Assuming a star formation efficiency of ϵ* ∼ 0.5, cosmic variance alone reduces the tension to a 2σ level, except for the most massive galaxy at z = 8. Additionally, incorporating a 0.3 dex lognormal dispersion in the stellar mass estimation brings the observed ρ*(>M*) at z ∼ 7–10 within 2σ. The tension is completely eliminated when we account for the gas stripped from backsplash haloes. These results highlight the importance of fully modelling uncertainties when interpreting observational data of rare objects. We use the constrained simulation, ELUCID, to investigate the descendants of high-z massive galaxies. Our findings reveal that a significant portion of these galaxies ultimately resides in massive haloes at z = 0 with $M_{\rm halo} \gt 10^{13}\, h^{-1}{\rm M_\odot }$. Moreover, a large fraction of local central galaxies in $M_{\rm halo} \geqslant 10^{14.5} \, h^{-1}{\rm M_\odot }$ haloes are predicted to contain substantial amounts of ancient stars formed in massive galaxies at z ∼ 8. This prediction can be tested by studying the structure and stellar population of central galaxies in present-day massive clusters.
Galaxy groups in the low-redshift Universe Lim, S. H; Mo, H. J; Lu, Yi ...
Monthly Notices of the Royal Astronomical Society,
09/2017, Volume:
470, Issue:
3
Journal Article
Peer reviewed
Open access
Abstract
We apply a halo-based group finder to four large redshift surveys, the 2MRS (Two Micron All-Sky Redshift Survey), 6dFGS (Six-degree Field Galaxy Survey), SDSS (Sloan Digital Sky Survey) and ...2dFGRS (Two-degree Field Galaxy Redshift Survey), to construct group catalogues in the low-redshift Universe. The group finder is based on that of Yang et al. but with an improved halo mass assignment so that it can be applied uniformly to various redshift surveys of galaxies. Halo masses are assigned to groups according to proxies based on the stellar mass/luminosity of member galaxies. The performances of the group finder in grouping galaxies according to common haloes and in halo mass assignments are tested using realistic mock samples constructed from hydrodynamical simulations and empirical models of galaxy occupation in dark matter haloes. Our group finder finds ∼94 per cent of the correct true member galaxies for 90–95 per cent of the groups in the mock samples; the halo masses assigned by the group finder are un-biased with respect to the true halo masses, and have a typical uncertainty of ∼0.2 dex. The properties of group catalogues constructed from the observational samples are described and compared with other similar catalogues in the literature.
We present the detection of the kinetic Sunyaev-Zel'dovich effect (kSZE) signals from groups of galaxies as a function of halo mass down to using the Planck cosmic microwave background maps and ...stacking about 40,000 galaxy systems with known positions, halo masses, and peculiar velocities. The signals from groups of different mass are constrained simultaneously to take care of the projection effects of nearby halos. The total kSZE flux within halos estimated implies that the gas fraction in halos is about the universal baryon fraction, even in low-mass halos, indicating that the "missing baryons" are found. Various tests performed show that our results are robust against systematic effects, such as contamination by infrared/radio sources and background variations, beam size effects, and contributions from halo exteriors. Combined with the thermal Sunyaev-Zel'dovich effect, our results indicate that the "missing baryons" associated with galaxy groups are contained in warm-hot media with temperatures between 105 and 106 K.
We present a new model to describe the galaxy-dark matter connection across cosmic time, which unlike the popular subhalo abundance-matching technique is self-consistent in that it takes account of ...the facts that (1) subhalos are accreted at different times and (2) the properties of satellite galaxies may evolve after accretion. Using observations of galaxy stellar mass functions (SMFs) out to z ~ 4, the conditional SMF at z ~ 0.1 obtained from Sloan Digital Sky Survey galaxy group catalogs, and the two-point correlation function (2PCF) of galaxies at z ~ 0.1 as a function of stellar mass, we constrain the relation between galaxies and dark matter halos over the entire cosmic history from z ~ 4 to the present. This relation is then used to predict the median assembly histories of different stellar mass components within dark matter halos (central galaxies, satellite galaxies, and halo stars). We also make predictions for the 2PCFs of high-z galaxies as function of stellar mass. Our main findings are the following: (1) Our model reasonably fits all data within the observational uncertainties, indicating that the LAMBDACDM concordance cosmology is consistent with a wide variety of data regarding the galaxy population across cosmic time. (2) At low-z, the stellar mass of central galaxies increases with halo mass as M super(0.3) and M super(> ~4.0) at the massive and low-mass ends, respectively. The ratio Mlow *,c/M reveals a maximum of ~0.03 at a halo mass M ~ 10 super(11.8) h super(-1) M sub(middot in circle), much lower than the universal baryon fraction (~0.17). At higher redshifts the maximum in Mlow *,c/M remains close to ~0.03, but shifts to higher halo mass. (3) The inferred timescale for the disruption of satellite galaxies is about the same as the dynamical friction timescale of their subhalos. (4) The stellar mass assembly history of central galaxies is completely decoupled from the assembly history of its host halo; the ratio Mlow *,c/M initially increases rapidly with time until the halo mass reaches ~10 super(12) h super(-1) M sub(middot in circle), at which point Mlow *,c/M ~ 0.03. Once M > ~10 super(12) h super(-1) M sub(middot in circle), there is little growth in Mlow *,c, causing the ratio Mlow *,c/M to decline. In Milky Way (MW)-sized halos more than half of the central stellar mass is assembled at z <, ~ 0.5. (5) In low-mass halos, the accretion of satellite galaxies contributes little to the formation of their central galaxies, indicating that most of their stars must have formed in situ. In massive halos more than half of the stellar mass of the central galaxy has to be formed in situ, and the accretion of satellites can only become significant at z <, ~ 2. (6) The total mass in halo stars is more than twice that of the central galaxy in massive halos, but less than 10% of Mlow *,c in MW-sized halos. (7) The 2PCFs of galaxies on small scales hold important information regarding the evolution of satellite galaxies, which at high-z is predicted to be much steeper than at low-z, especially for more massive galaxies. We discuss various implications of our findings regarding the formation and evolution of galaxies in a LambdaCDM cosmology.
Using a large galaxy group catalog constructed from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) with an adaptive halo-based group finder, we investigate the luminosity and stellar mass ...functions for different populations of galaxies (central versus satellite, red versus blue, and galaxies in groups of different masses) and for groups themselves. The conditional stellar mass function (CSMF), which describes the stellar distribution of galaxies in halos of a given mass for central and satellite galaxies can be well modeled with a log-normal distribution and a modified Schechter form, respectively. On average, there are about three times as many central galaxies as satellites. Among the satellite population, there are in general more red galaxies than blue ones. For the central population, the luminosity function is dominated by red galaxies at the massive end, and by blue galaxies at the low-mass end. At the very low mass end (M * 109 h -2 M ), however, there is a marked increase in the number of red centrals. We speculate that these galaxies are located close to large halos so that their star formation is truncated by the large-scale environments. The stellar mass function of galaxy groups is well described by a double power law, with a characteristic stellar mass at ~4 X 1010 h -2 M . Finally, we use the observed stellar mass function of central galaxies to constrain the stellar mass-halo mass relation for low-mass halos, and obtain M *,c M 4.9 h for Mh 1011 h -1 M .
We use the kinematics of satellite galaxies that orbit around the central galaxy in a dark matter halo to infer the scaling relations between halo mass and central galaxy properties. Using galaxies ...from the Sloan Digital Sky Survey, we investigate the halo mass-luminosity relation (MLR) and the halo mass-stellar mass relation (MSR) of central galaxies. In particular, we focus on the dependence of these scaling relations on the colour of the central galaxy. We find that red central galaxies on average occupy more massive haloes than blue central galaxies of the same luminosity. However, at fixed stellar mass there is no appreciable difference in the average halo mass of red and blue centrals, especially for M
*≲ 1010.5
h
−2 M⊙. This indicates that stellar mass is a better indicator of halo mass than luminosity. Nevertheless, we find that the scatter in halo masses at fixed stellar mass is non-negligible for both red and blue centrals. It increases as a function of stellar mass for red centrals but shows a fairly constant behaviour for blue centrals. We compare the scaling relations obtained in this paper with results from other independent studies of satellite kinematics, with results from a SDSS galaxy group catalog, from galaxy-galaxy weak lensing measurements and from subhalo abundance matching studies. Overall, these different techniques yield MLRs and MSRs in fairly good agreement with each other (typically within a factor of 2), indicating that we are converging on an accurate and reliable description of the galaxy-dark matter connection. We briefly discuss some of the remaining discrepancies among the various methods.
We investigate the ability of current implementations of galaxy group finders to recover colour-dependent halo occupation statistics. To test the fidelity of group catalogue inferred statistics, we ...run three different group finders used in the literature over a mock that includes galaxy colours in a realistic manner. Overall, the resulting mock group catalogues are remarkably similar, and most colour-dependent statistics are recovered with reasonable accuracy. However, it is also clear that certain systematic errors arise as a consequence of correlated errors in group membership determination, central/satellite designation, and halo mass assignment. We introduce a new statistic, the halo transition probability (HTP), which captures the combined impact of all these errors. As a rule of thumb, errors tend to equalize the properties of distinct galaxy populations (i.e. red versus blue galaxies or centrals versus satellites), and to result in inferred occupation statistics that are more accurate for red galaxies than for blue galaxies. A statistic that is particularly poorly recovered from the group catalogues is the red fraction of central galaxies as a function of halo mass. Group finders do a good job in recovering galactic conformity, but also have a tendency to introduce weak conformity when none is present. We conclude that proper inference of colour-dependent statistics from group catalogues is best achieved using forward modelling (i.e. running group finders over mock data) or by implementing a correction scheme based on the HTP, as long as the latter is not too strongly model dependent.
Galaxy clustering and galaxy–galaxy lensing probe the connection between galaxies and their dark matter haloes in complementary ways. Since the clustering of dark matter haloes depends on cosmology, ...the halo occupation statistics inferred from the observed clustering properties of galaxies are degenerate with the adopted cosmology. Consequently, different cosmologies imply different mass-to-light ratios for dark matter haloes. Galaxy–galaxy lensing, which yields direct constraints on the actual mass-to-light ratios, can therefore be used to break this degeneracy, and thus to constrain cosmological parameters. In this paper, we establish the link between galaxy luminosity and dark matter halo mass using the conditional luminosity function (CLF), Φ(L|M) dL, which gives the number of galaxies with luminosities in the range L± dL/2 that reside in a halo of mass M. We constrain the CLF parameters using the galaxy luminosity function and the luminosity dependence of the correlation lengths of galaxies. The resulting CLF models are used to predict the galaxy–galaxy lensing signal. For a cosmology that agrees with constraints from the cosmic microwave background, i.e. (Ωm, σ8) = (0.238, 0.734), the model accurately fits the galaxy–galaxy lensing data obtained from the Sloan Digital Sky Survey. For a comparison cosmology with (Ωm, σ8) = (0.3, 0.9), however, we can accurately fit the luminosity function and clustering properties of the galaxy population, but the model predicts mass-to-light ratios that are too high, resulting in a strong overprediction of the galaxy–galaxy lensing signal. We conclude that the combination of galaxy clustering and galaxy–galaxy lensing is a powerful probe of the galaxy–dark matter connection, with the potential to yield tight constraints on cosmological parameters. Since this method mainly probes the mass distribution on relatively small (non-linear) scales, it is complementary to constraints obtained from the galaxy power spectrum, which mainly probes the large-scale (linear) matter distribution.
We use the halo occupation model to calibrate galaxy group finders in magnitude limited redshift surveys. Because, according to the current scenario of structure formation, galaxy groups are ...associated with cold dark matter (CDM) haloes, we make use of the properties of the halo population in the design of our group finder. The method starts with an assumed mass-to-light ratio to assign a tentative mass to each group. This mass is used to estimate the size and velocity dispersion of the underlying halo that hosts the group, which in turn is used to determine group membership (in redshift space). This procedure is repeated until no further changes occur in group memberships. We find that the final groups selected this way are insensitive to the mass-to-light ratio assumed. We use mock catalogues, constructed using the conditional luminosity function (CLF), to test the performance of our group finder in terms of completeness of true members and contamination by interlopers. Our group finder is more successful than the conventional friends-of-friends (FOF) group finder in assigning galaxies in common dark matter haloes to a single group. We apply our group finder to the 2-degree Field Galaxy Redshift Survey (2dFGRS) and compare the resulting group properties with model predictions based on the CLF. For the ΛCDM concordance cosmology, we find a clear discrepancy between the model and data in the sense that the model predicts too many rich groups. In order to match the observational results, we have to either increase the mass-to-light ratios of rich clusters to a level significantly higher than current observational estimates, or to assume σ8≃ 0.7, compared with the concordance value of 0.9.
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