Theoretical models of the halo occupation distribution: Separating central and satellite galaxies

Zheng Zheng, Andreas A. Berlind, David H. Weinberg, Andrew J. Benson, Carlton M. Baugh, Shaun Cole, Romeel S Dave, Carlos S. Frenk, Neal Katz, Cedric G. Lacey

Research output: Contribution to journalArticle

436 Citations (Scopus)

Abstract

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 semianalytic (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 W galaxies of a particular class. In agreement with earlier results for dark matter subhalos, we find that the mean occupation function 〈N〉M 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. Since the number of central galaxies is always zero or one, the width of P(N|M) is narrower than a Poisson distribution at low N and approaches Poisson at high N. 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 ≈ 14M min (SPH) or M1 ≈ 18Mmin (SA). The stellar population age of central galaxies correlates with halo mass, and this correlation explains much of the age dependence of the galaxy HOD. The mean occupation number of young galaxies exhibits a local minimum at M ∼ 10M min where halos are too massive to host a young central galaxy but not massive enough to host satellites. Using the SA model, 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.

Original languageEnglish (US)
Pages (from-to)791-809
Number of pages19
JournalAstrophysical Journal
Volume633
Issue number2 I
DOIs
StatePublished - Nov 10 2005
Externally publishedYes

Fingerprint

occupation
halos
galaxies
hydrodynamics
dark matter
distribution
parameterization
power law
step functions
thresholds
galactic evolution
history
prediction

Keywords

  • Cosmology: theory
  • Galaxies: formation
  • Galaxies: halos
  • Large
  • Scale structure of universe

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Zheng, Z., Berlind, A. A., Weinberg, D. H., Benson, A. J., Baugh, C. M., Cole, S., ... Lacey, C. G. (2005). Theoretical models of the halo occupation distribution: Separating central and satellite galaxies. Astrophysical Journal, 633(2 I), 791-809. https://doi.org/10.1086/466510

Theoretical models of the halo occupation distribution : Separating central and satellite galaxies. / Zheng, Zheng; Berlind, Andreas A.; Weinberg, David H.; Benson, Andrew J.; Baugh, Carlton M.; Cole, Shaun; Dave, Romeel S; Frenk, Carlos S.; Katz, Neal; Lacey, Cedric G.

In: Astrophysical Journal, Vol. 633, No. 2 I, 10.11.2005, p. 791-809.

Research output: Contribution to journalArticle

Zheng, Z, Berlind, AA, Weinberg, DH, Benson, AJ, Baugh, CM, Cole, S, Dave, RS, Frenk, CS, Katz, N & Lacey, CG 2005, 'Theoretical models of the halo occupation distribution: Separating central and satellite galaxies', Astrophysical Journal, vol. 633, no. 2 I, pp. 791-809. https://doi.org/10.1086/466510
Zheng Z, Berlind AA, Weinberg DH, Benson AJ, Baugh CM, Cole S et al. Theoretical models of the halo occupation distribution: Separating central and satellite galaxies. Astrophysical Journal. 2005 Nov 10;633(2 I):791-809. https://doi.org/10.1086/466510
Zheng, Zheng ; Berlind, Andreas A. ; Weinberg, David H. ; Benson, Andrew J. ; Baugh, Carlton M. ; Cole, Shaun ; Dave, Romeel S ; Frenk, Carlos S. ; Katz, Neal ; Lacey, Cedric G. / Theoretical models of the halo occupation distribution : Separating central and satellite galaxies. In: Astrophysical Journal. 2005 ; Vol. 633, No. 2 I. pp. 791-809.
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