Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userObservational Measures of Halo Properties Beyond Mass
90
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Different properties of dark matter haloes, including growth rate, concentration, interaction history, and spin, correlate with environment in unique, scale-dependent ways. While these halo properties are not directly observable, galaxies will inherit their host haloes correlations with environment. In this paper, we show how these characteristic environmental signatures allow using measurements of galaxy environment to constrain which dark matter halo properties are most tightly connected to observable galaxy properties. We show that different halo properties beyond mass imprint distinct scale-dependent signatures in both the galaxy two-point correlation function and the distribution of distances to galaxies kth nearest neighbours, with features strong enough to be accessible even with low-resolution (e.g., grism) spectroscopy at higher redshifts. As an application, we compute observed two-point correlation functions for galaxies binned by half-mass radius at z=0 from the Sloan Digital Sky Survey, showing that classic galaxy size models (i.e., galaxy size being proportional to halo spin) as well as other recent proposals show significant tensions with observational data. We show that the agreement with observed clustering can be improved with a simple empirical model in which galaxy size correlates with halo growth.
rate research
Read More
Secondary halo properties beyond mass, such as the mass accretion rate (MAR), concentration, and the half mass scale, are essential in understanding the formation of large-scale structure and dark matter halos. In this paper, we study the impact of secondary halo properties on the galaxy-galaxy lensing observable, $DeltaSigma$. We build an emulator trained on N-body simulations to model $DeltaSigma$ and quantify the impact of different secondary parameters on the $DeltaSigma$ profile. We focus on the impact of MAR on $DeltaSigma$. We show that a 3$sigma$ detection of variations in MAR at fixed halo mass could be achieved with the Hyper Suprime Cam survey in combination with a proxy for MAR with scatter $sigma_{Gamma_mathrm{dyn}|mathrm{obs}}<1.5$. We show that the full radial profile of $DeltaSigma$ depends on secondary properties at fixed halo mass. Consequently, an emulator that can perform full shape fitting yields better than 2 times improvement upon the constraints on MAR than only using the outer part of the halo. Finally, we highlight that miscentering and MAR impact the radial profile of $DeltaSigma$ in a similar fashion, implying that miscentering and MAR need to be modeled jointly for unbiased estimates of both effects. We show that present-day lensing data sets have the statistical capability to place constraints on halo MAR. Our analysis opens up new possibilities for observationally measuring the assembly history of the dark matter halos that host galaxies and clusters.
We examine how the mass assembly of central galaxies depends on their location in the cosmic web. The HORIZON-AGN simulation is analysed at z~2 using the DISPERSE code to extract multi-scale cosmic filaments. We find that the dependency of galaxy properties on large-scale environment is mostly inherited from the (large-scale) environmental dependency of their host halo mass. When adopting a residual analysis that removes the host halo mass effect, we detect a direct and non-negligible influence of cosmic filaments. Proximity to filaments enhances the build-up of stellar mass, a result in agreement with previous studies. However, our multi-scale analysis also reveals that, at the edge of filaments, star formation is suppressed. In addition, we find clues for compaction of the stellar distribution at close proximity to filaments. We suggest that gas transfer from the outside to the inside of the haloes (where galaxies reside) becomes less efficient closer to filaments, due to high angular momentum supply at the vorticity-rich edge of filaments. This quenching mechanism may partly explain the larger fraction of passive galaxies in filaments, as inferred from observations at lower redshifts.
We show that the ratio between the stellar mass of central galaxy and the mass of its host halo, $f_c equiv M_{*,c}/M_{rm h}$, can be used as an observable proxy of halo assembly time, in that galaxy groups with higher $f_c$ assembled their masses earlier. Using SDSS groups of Yang et al., we study how $f_c$ correlates with galaxy properties such as color, star formation rate, metallicity, bulge to disk ratio, and size. Central galaxies of a given stellar mass in groups with $f_c>0.02$ tend to be redder in color, more quenched in star formation, smaller in size, and more bulge dominated, as $f_c$ increases. The trends in color and star formation appear to reverse at $f_c<0.02$, reflecting a down-sizing effect that galaxies in massive halos formed their stars earlier although the host halos themselves assembled later (lower $f_c$). No such reversal is seen in the size of elliptical galaxies, suggesting that their assembly follows halo growth more closely than their star formation. Satellite galaxies of a given stellar mass in groups of a given halo mass tend to be redder in color, more quenched in star formation and smaller in size as $f_c$ increases. For a given stellar mass, satellites also tend to be smaller than centrals. The trends are stronger for lower mass groups. For groups more massive than $sim 10^{13}{rm M}_odot$, a weak reversed trend is seen in color and star formation. The observed trends in star formation are qualitatively reproduced by an empirical model based on halo age abundance matching, but not by a semi-analytical model tested here.
We carry out a systematic investigation of the total mass density profile of massive (Mstar>2e11 Msun) early-type galaxies and its dependence on galactic properties and host halo mass with the aid of a variety of lensing/dynamical data and large mock galaxy catalogs. The latter are produced via semi-empirical models that, by design, are based on just a few basic input assumptions. Galaxies, with measured stellar masses, effective radii and S{e}rsic indices, are assigned, via abundance matching relations, host dark matter halos characterized by a typical LCDM profile. Our main results are as follows: (i) In line with observational evidence, our semi-empirical models naturally predict that the total, mass-weighted density slope at the effective radius gamma is not universal, steepening for more compact and/or massive galaxies, but flattening with increasing host halo mass. (ii) Models characterized by a Salpeter or variable initial mass function and uncontracted dark matter profiles are in good agreement with the data, while a Chabrier initial mass function and/or adiabatic contractions/expansions of the dark matter halos are highly disfavored. (iii) Currently available data on the mass density profiles of very massive galaxies (Mstar>1e12 Msun), with Mhalo>3e14 Msun, favor instead models with a stellar profile flatter than a S{e}rsic one in the very inner regions (r<3-5 kpc), and a cored NFW or Einasto dark matter profile with median halo concentration a factor of ~2 or <1.3, respectively, higher than those typically predicted by N-body numerical simulations.
We use KiDS weak lensing data to measure variations in mean halo mass as a function of several key galaxy properties (namely: stellar colour, specific star formation rate, Sersic index, and effective radius) for a volume-limited sample of GAMA galaxies in a narrow stellar mass range ($M_* sim 2$--$5 times 10^{10}$ Msol). This mass range is particularly interesting, inasmuch as it is where bimodalities in galaxy properties are most pronounced, and near to the break in both the galaxy stellar mass function and the stellar-to-halo mass relation (SHMR). In this narrow mass range, we find that both size and Sersic index are better predictors of halo mass than either colour or SSFR, with the data showing a slight preference for Sersic index. In other words, we find that mean halo mass is more tightly correlated with galaxy structure than either past star formation history or current star formation rate. Our results lead to an approximate lower bound on the dispersion in halo masses among $log M_* approx {10.5}$ galaxies: we find that the dispersion is $gtrsim 0.3$ dex. This would imply either that offsets from the mean SHMR are closely coupled to size/structure, or that the dispersion in the SHMR is larger than past results have suggested. Our results thus provide new empirical constraints on the relationship between stellar and halo mass assembly at this particularly interesting mass range.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
