The halo model and numerical simulations

Recently there has been a lot of attention focussed on a virialized halo-based approach to understanding the properties of the matter and galaxy power spectrum. A key ingredient in this model is the number and distribution of galaxies within dark matter halos as a function of mass. This quantity has been predicted from semi-analytic modeling and from fits to observational data. Here we present predictions for the occupation number and spatial distribution of sub-halos based on a high-resolution hydrodynamical simulation including cooling, star-formation and feedback.