Frank van den Bosch

Halo Occupation Modelling
• PARADIGM: Galaxies live in extended Cold Dark Matter Haloes.
• Dark Matter Haloes are a biased tracer of DM mass distribution.
• Halo bias b(M) is cosmology dependent and follows from EPS and/or
• N -body simulations.
• It allows a computation of halo-halo correlation function ξhh(r|M)
• Halo Occupation Models link ξhh(r|M) to ξgg(r) by modelling the halo
• occupation distribution P (N|M), which describes the galaxy bias.
• This yields interesting constraints on 〈Ngal〉(M) and on cosmology
(e.g., Seljak 2000; Scoccimarro et al. 2001; Berlind & Weinberg 2002; Magiocchetti & Porciani 2003;
Abazajian et al. 2004; Collister & Lahav 2004; Zehavi et al. 2004; Zheng et al. 2005)
• However, galaxy bias bgal = bgal(L, type, ...).
• To model bgal(L) we introduce the Conditional Luminosity Function (CLF)
• Φ(L|M) which describes average number of galaxies of luminosity L in
• a halo of mass M .