We use a modified version of the halo-based group finder developed by Yang et al. to select galaxy groups from Sloan Digital Sky Survey (SDSS DR4). In first step, combination two methods is used identify centers potential and estimate their characteristic luminosity. Using an iterative approach, adaptive then uses average mass-to-light ratios groups, obtained previous iteration, assign tentative mass each group. This size velocity dispersion underlying halo that hosts group, which in turn...

We use a statistical approach to determine the relationship between stellar masses of galaxies and dark matter halos in which they reside. obtain parameterized stellar-to-halo mass (SHM) relation by populating subhalos an N-body simulation with requiring that observed function be reproduced. find good agreement constraints from galaxy-galaxy lensing predictions semi-analytic models. Using this mapping, positions obtained simulation, we our model for galaxy two-point correlation (CF) as are...

We investigate the effects of changes in cosmological parameters between WMAP 1st, 3rd, and 5th year results on structure dark matter haloes. use a set simulations that cover 5 decades halo mass ranging from scales dwarf galaxies (V_c ~30 km/s) to clusters ~ 1000 km/s). find concentration relation is power law all three cosmologies. However slope shallower zero point lower moving WMAP1 WMAP5 WMAP3. For haloes log(M_200/Msun) = 10, 12, 14 differences parameter WMAP3 are factor 1.55, 1.41,...

We derive new constraints on the mass of Milky Way's dark matter halo, based 2401 rigorously selected blue horizontal-branch halo stars from SDSS DR6. This sample enables construction full line-of-sight velocity distribution at different galactocentric radii. To interpret these distributions, we compare them to matched mock observations drawn two cosmological galaxy formation simulations designed resemble Way. procedure results in an estimate circular curve ~60 kpc, which is found be...

Using a large galaxy group catalogue constructed from the Sloan Digital Sky Survey Data Release 2, we investigate correlation between various properties and halo mass. We split population of galaxies in early-types, late-types intermediate-types, based on their colour specific star formation rate. At fixed luminosity, late- (early-)type fraction increases (decreases) with decreasing Most importantly, this mass dependence is smooth persists over entire range probed, without any break or...

We use the conditional luminosity function Φ(L | M) dL, which gives number of galaxies with luminosities in range L± d L/2 that reside a halo mass M, to link distribution dark matter haloes. Starting from density haloes predicted by current models structure formation, we seek form reproduces galaxy and dependence clustering strength. test comparing resulting mass-to-light ratios constraints Tully—Fisher (TF) relation clusters. A comparison between model predictions observations yields...

Satellite galaxies in groups and clusters are more likely to have low star formation rates (SFRs) lie on the 'red sequence' than central ('field') galaxies. Using galaxy group/cluster catalogues from Sloan Digital Sky Survey Data Release 7, together with a high-resolution, cosmological N-body simulation track satellite orbits, we examine histories quenching time-scales of satellites Mstar > 5 × 109 M⊙ at z ≈ 0. We first explore infall histories: group preprocessing ejected orbits critical...

We use a series of cosmological N-body simulations for flat Λ cold dark matter (ΛCDM) cosmology to investigate the structural properties haloes, at redshift zero, in mass range 3 × 109h−1 ≲Mvir ≲ 1013h−1 M⊙. These include concentration parameter, c, spin λ, and mean axis ratio, ⁠. For concentration–mass relation we find c∝ agreement with model proposed by Bullock et al., but inconsistent alternative Eke al. The normalization relation, however, is 15 per cent lower than suggested results λ...

We use the halo occupation model to calibrate galaxy group finders in magnitude-limited redshift surveys. Since, according current scenario of structure formation, groups are associated with cold dark matter halos, we make properties population design our finder. The method starts an assumed mass-to-light ratio assign a tentative mass each group. This is used estimate size and velocity dispersion underlying that hosts group, which turn determine membership (in space). procedure repeated...

According to the current paradigm, galaxies initially form as disc at centres of their own dark matter haloes. During subsequent evolution, they may undergo a transformation red, early-type galaxy, thus giving rise build-up red sequence. Two important, outstanding questions are (i) which mechanisms most important and (ii) in what environment do occur. In this paper, we study impact that operate only on satellite galaxies, such strangulation, ram-pressure stripping galaxy harassment. Using...

We present a new model to describe the galaxy-dark matter connection across cosmic time, which unlike popular subhalo abundance matching technique is self-consistent in that it takes account of facts (i) subhalos are accreted at different times, and (ii) properties satellite galaxies may evolve after accretion. Using observations galaxy stellar mass functions out $z \sim 4$, conditional function $z\sim 0.1$ obtained from SDSS group catalogues, two-point correlation (2PCF) as mass, we...

We investigate various galaxy occupation statistics of dark matter halos using a large group catalog constructed from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) with an adaptive halo-based finder. The conditional luminosity function (CLF) is measured separately for all, red, and blue galaxies, as well in terms central satellite galaxies. CLFs galaxies can be modeled lognormal distribution modified Schechter form, respectively. About 85% about 80% masses Mh≳ 1014 h−1 M☉ are red...

Using a large galaxy group catalog constructed from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) with an adaptive halo-based finder, we investigate luminosity and stellar mass functions for different populations of galaxies (central versus satellite, red blue, in groups masses) themselves. The conditional function (CSMF), which describes distribution halos given central satellite can be well modeled log-normal modified Schechter form, respectively. On average, there are about three...

Accurately predicting the demographics of dark matter (DM) substructure is paramount importance for many fields astrophysics, including gravitational lensing, galaxy evolution, halo occupation modelling, and constraining nature DM. Because its strongly non-linear nature, DM typically modelled using N-body simulations, which reveal that large fractions subhaloes undergo complete disruption. In this paper, we use both analytical estimates idealized numerical simulations to investigate whether...

We use the kinematics of satellite galaxies that orbit around central galaxy in a dark matter halo to infer scaling relations between mass and properties. Using from Sloan Digital Sky Survey, we investigate mass–luminosity relation (MLR) mass–stellar (MSR) galaxies. In particular, focus on dependence these colour galaxy. find red average occupy more massive haloes than blue same luminosity. However, at fixed stellar there is no appreciable difference centrals, especially for M*≲ 1010.5h−2...

To gain understanding of the complicated, non-linear, and numerical processes associated with tidal evolution dark matter subhaloes in simulation, we perform a large suite idealized simulations that follow individual N-body fixed, analytical host halo potential. By varying both physical parameters, investigate under what conditions undergo disruption. We confirm conclusions from our more assessment van den Bosch et al. most disruption is origin; as long subhalo resolved sufficient mass force...

We present a new method that simultaneously solves for cosmology and galaxy bias on non-linear scales. The uses the halo model to analytically describe (non-linear) matter distribution, conditional luminosity function (CLF) specify occupation statistics. For given choice of cosmological parameters, this can be used predict function, as well two-point correlation functions galaxies, galaxy–galaxy lensing signal, both scale luminosity. These observables have been reliably measured from Sloan...

ABSTRACT The circumgalactic medium (CGM), i.e. the gaseous haloes around galaxies, is both reservoir of gas that fuels galaxy growth and repository expelled by galactic winds. Most cosmological, hydrodynamical simulations focus their computational effort on galaxies themselves treat CGM more coarsely, which means small-scale structure cannot be resolved. We get this issue running zoom-in a Milky Way-mass with standard mass refinement additional uniform spatial within virial radius. This...

We present high-resolution Hα rotation curves for a sample of 15 dwarf and low surface brightness galaxies. From these we derive limits on the slopes central mass distributions, using both direct inversion detailed models. Assuming that density distributions dark matter halos follow power law at small radii, ρ(r) ∝ r-α, find inner in range 0 ≲ α 1 most Thus, even with relatively high spatial resolution presented here, are poorly constrained. In general constant cores (α = 0) provide somewhat...

We use the extended Press-Schechter formalism to investigate rate at which cold dark matter haloes accrete mass. discuss shortcomings of previous methods that have been used compute mass accretion histories haloes, and present an improved method based on N-branch merger tree algorithm Somerville & Kolatt. show this no longer suffers from inconsistencies in halo formation times, compare its predictions with high-resolution N-body simulations. Although overall agreement is reasonable, there...

We use the conditional luminosity function (CLF) and data from 2-degree Field Galaxy Redshift Survey (2dFGRS) to constrain average relation between light mass in a Lambda cold dark matter (ΛCDM) cosmology with Ωm= 0.23 σ8= 0.74 (hereafter WMAP3 cosmology).Reproducing observed dependence of galaxy two-point correlation results mass-to-light ratios that are ∼35 per cent lower than those ΛCDM 0.3 0.9 WMAP1 cosmology).This removes an important problem previous halo occupation models which had...

We use observed rotation velocity-luminosity (VL) and size-luminosity (RL) relations to single out a specific scenario for disk galaxy formation in the LCDM cosmology. Our model involves four independent log-normal random variables: dark-halo concentration c, spin lam_gal, mass fraction m_gal, stellar mass-to-light ratio M/L_I. A simultaneous match of VL RL zero points with adiabatic contraction requires low-c halos, but this has V_2.2~1.8 V_vir (where V_2.2 are circular velocity at 2.2...

The standard cold dark matter (CDM) model has recently been challenged by the claim that dwarf galaxies have haloes with constant-density cores, whereas CDM predicts steeply cusped density distributions. Consequently, numerous alternative candidates proposed. In this paper we scrutinize observational evidence for incongruity between and model. To end, analyse rotation curves of 20 late-type studied Swaters. Taking effects beam smearing adiabatic contraction into account, fit mass models to...

We construct a large data set of global structural parameters for 1300 field and cluster spiral galaxies explore the joint distribution luminosity L, optical rotation velocity V, disk size R at I 2MASS K bands. The I- K-band velocity-luminosity (VL) relations have log slopes 0.29 0.27, respectively, with σln(VL) ~ 0.13, show small dependence on color morphological type in sense that redder, earlier rotate faster than bluer, later most luminosities. VL relation bands is independent surface...

We reexamine the disk-halo decompositions of rotation curves low surface brightness (LSB) galaxies with Vmax ≥ 80 km s-1, taking full account effects beam smearing. show that spatial resolution data is not sufficient to put any meaningful constraints on density profiles dark halos, or cosmological parameters. This in strong contrast claims made literature these LSB are only consistent matter halos shallow central cusps, and it has important implications regarding galaxies, such as...