# Exploring the halo occupation of AGN using dark-matter cosmological simulations

## TL;DR

This paper presents a semi-empirical model linking AGN distribution to dark matter halos in cosmological simulations, revealing insights into their halo occupation and clustering properties, with implications for black-hole fueling physics.

## Contribution

The model uniquely combines empirical galaxy-halo relations with AGN occupation data to infer AGN halo occupation and clustering in dark matter simulations.

## Key findings

- AGN occupy halos with a broad mass distribution centered around 10^12 h^-1 M_sun
- Clustering of AGN weakly depends on luminosity and redshift
- Satellite AGN fraction increases with halo mass, contrasting some observations

## Abstract

A semi-empirical model is presented that describes the distribution of Active Galactic Nuclei (AGN) on the cosmic web. It populates dark-matter halos in N-body simulations (MultiDark) with galaxy stellar masses using empirical relations based on abundance matching techniques, and then paints accretion events on these galaxies using state-of-the-art measurements of the AGN occupation of galaxies. The explicit assumption is that the large-scale distribution of AGN is independent of the physics of black-hole fueling. The model is shown to be consistent with current measurements of the two-point correlation function of AGN samples. It is then used to make inferences on the halo occupation of the AGN population. Mock AGN are found in halos with a broad distribution of masses with a mode of $\approx 10^{12}\,h^{-1} \, M_{\odot}$ and a tail extending to cluster-size halos. The clustering properties of the model AGN depend only weakly on accretion luminosity and redshift. The fraction of satellite AGN in the model increases steeply toward more massive halos, in contrast with some recent observational results. This discrepancy, if confirmed, could point to a dependence of the halo occupation of AGN on the physics of black-hole fueling.