Clustering and halo occupation of AGNs using a semi-analytic model of galaxy formation

We investigate clustering properties of active galactic nuclei (AGNs) using a new version of our semi-analytic model of galaxy and AGN formation.  We focus on whether X-ray AGNs triggered by galaxy major and minor mergers and disc instabilities are able to explain the observationally estimated host dark matter halo.  Our model can reproduce the AGN luminosity functions at 0 < z < 6.0 by introducing the gas accretion timescale depending on black hole mass and accreted gas mass.  The predicted effective halo mass is ~10^13 Msun/h at z < 1, which is consistent with most of the current observations of AGN clustering.  We also compare the predicted two-point correlation function, the halo occupation distribution, and the AGN satellite fraction of X-ray AGNs with observations.  Overall, these quantities are in agreement with the observations.  In particular, the halo occupation of satellite AGNs is in qualitative agreement with the observations.  Our results suggest that at least part of the observed clustering properties and the inferred host halo mass of X-ray AGNs can be explained by the AGN activity caused by galaxy major and minor mergers and disc instabilities.