Revisiting HOD model assumptions: the impact of AGN feedback and
  assembly bias
  The standard Halo Occupation Distribution (HOD) models were originally
developed based on results from semi-analytic and hydrodynamical galaxy
formation models. Those models have since progressed, in particular to include
AGN feedback to match the galaxy luminosity function in a universe with the
observed baryon fraction. AGN feedback affects the relationship between galaxy
stellar mass and luminosity, in particular making the relationship
non-monotonic. For matched number density samples, galaxies in
luminosity-threshold samples occupy a different range of halo masses from those
in stellar-mass-threshold samples. We find that the shapes of the HODs of
luminosity-threshold samples are slightly more complicated in semi-analytic
galaxy formation models that include AGN feedback than are assumed by standard
HOD models. We also find that subhalo abundance matching (SHAM) does not
preserve these non-standard shapes. We show that catalogues created using SHAM
and the semi-analytic model Galform that have the same large-scale 2-point
clustering by construction have different void probability functions (VPFs) in
both real and redshift space. We find that these differences arise from the
different HOD shapes, as opposed to assembly bias, which indicates that the VPF
could be used to test the suitability of an HOD model with real data.
