This is the second paper of a series that reports on our investigation of the clustering properties of AGNs in the ROSAT All-Sky Survey ( RASS ) through cross-correlation functions ( CCFs ) with Sloan Digital Sky Survey ( SDSS ) galaxies .
In this paper , we apply the Halo Occupation Distribution ( HOD ) model to the CCFs between the RASS Broad-line AGNs with SDSS Luminous Red Galaxies ( LRGs ) in the redshift range 0.16 < z < 0.36 that was calculated in paper I .
In our HOD modeling approach , we use the known HOD of LRGs and constrain the HOD of the AGNs by a model fit to the CCF .
For the first time , we are able to go beyond quoting merely a ‘ typical ’ AGN host halo mass , M _ { h } , and model the full distribution function of AGN host dark matter halos .
In addition , we are able to determine the large-scale bias and the mean M _ { h } more accurately .
We explore the behavior of three simple HOD models .
Our first model ( Model A ) is a truncated power-law HOD model in which all AGNs are satellites .
With this model , we find an upper limit to the slope ( \alpha ) of the AGN HOD that is far below unity .
The other two models have a central component , which has a step function form , where the HOD is constant above a minimum mass , without ( Model B ) or with ( Model C ) an upper mass cutoff , in addition to the truncated power-law satellite component , similar to the HOD that is found for galaxies .
In these two models we find that the upper limits on \alpha are still below unity , with \alpha \lesssim 0.95 and \alpha \lesssim 0.84 for Model B and C respectively .
Our analysis suggests that the satellite AGN occupation increases slower than , or may even decrease with , M _ { h } in contrast to the satellite HODs of luminosity-threshold samples of galaxies , which , in contrast , grow approximately as \langle N _ { s } \rangle \propto M _ { h } ^ { \alpha } with \alpha \approx 1 .
These results are consistent with observations that the AGN fraction in groups and clusters decreases with richness .