The evolution of the galaxy content of dark matter haloes

TL;DR

This study compares galaxy formation models using the halo occupation distribution framework across redshifts, revealing similarities and differences, and providing a simple model for HOD evolution to aid future galaxy surveys.

Contribution

It introduces a simple parametrization of HOD evolution across redshifts based on two galaxy formation models, highlighting the diagnostic power of the central-to-satellite halo mass ratio.

Findings

Models show remarkable similarity in galaxy content predictions.

Differences are sensitive to AGN heating at low densities.

The ratio of halo masses for central and satellite galaxies is a key diagnostic.

Abstract

We use the halo occupation distribution (HOD) framework to characterise the predictions from two independent galaxy formation models for the galactic content of dark matter haloes and its evolution with redshift. Our galaxy samples correspond to a range of fixed number densities defined by stellar mass and span $0 \le z \le 3$. We find remarkable similarities between the model predictions. Differences arise at low galaxy number densities which are sensitive to the treatment of heating of the hot halo by active galactic nuclei. The evolution of the form of the HOD can be described in a relatively simple way, and we model each HOD parameter using its value at $z=0$ and an additional evolutionary parameter. In particular, we find that the ratio between the characteristic halo masses for hosting central and satellite galaxies can serve as a sensitive diagnostic for galaxy evolution models. Our results can be used to test and develop empirical studies of galaxy evolution and can facilitate the construction of mock galaxy catalogues for future surveys.