Theoretical Models of the Halo Occupation Distribution: Separating Central and Satellite Galaxies

Details Theoretical Models of the Halo Occupation Distribution: Separating Central and Satellite Galaxies Theoretical Models of the Halo Occupation Distribution: Separating Central and Satellite Galaxies

2004-08-30

arxiv.org/abs/astro-ph/0408564v2

Astrophys.J.633:791-809,2005

Astronomy and Astrophysics

Astrophysics

38 pages, 13 figures. Figures are added to show model predictions on CLF and the conditional mass distribution of halos hostin

Scientific paper

10.1086/466510

The halo occupation distribution (HOD) describes the relation between galaxies and dark matter at the level of individual dark matter halos. The properties of galaxies residing at the centers of halos differ from those of satellite galaxies because of differences in their formation histories. Using a smoothed particle hydrodynamics (SPH) simulation and a semi-analytic (SA) galaxy formation model, we examine the separate contributions of central and satellite galaxies to the HOD, more specifically to the probability P(N|M) that a halo of virial mass M contains N galaxies of a particular class. In agreement with earlier results for dark matter subhalos, we find that the mean occupation function for galaxies above a baryonic mass threshold can be approximated by a step function for central galaxies plus a power law for satellites, and that the distribution of satellite numbers is close to Poisson at fixed halo mass. For galaxy samples defined by different baryonic mass thresholds, there is a nearly linear relation between the minimum halo mass Mmin required to host a central galaxy and the mass M1 at which an average halo hosts one satellite, with M1 ~ 14 Mmin (SPH) or M1 ~ 18 Mmin (SA). The mean occupation number of young galaxies exhibits a local minimum at M ~ 10 Mmin where halos are too massive to host a young central galaxy but not massive enough to host satellites. We show that the conditional galaxy mass function at fixed halo mass cannot be described by a Schechter function because central galaxies produce a "bump" at high masses. We suggest parameterizations for the HOD and the conditional luminosity function that can be used to model observed galaxy clustering. Many of our predictions are in good agreement with recent results inferred from clustering in the Sloan Digital Sky Survey.

Affiliated with

Also associated with

No associations

Rating

Theoretical Models of the Halo Occupation Distribution: Separating Central and Satellite Galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Theoretical Models of the Halo Occupation Distribution: Separating Central and Satellite Galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Theoretical Models of the Halo Occupation Distribution: Separating Central and Satellite Galaxies will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-688911