The Swift/BAT AGN Spectroscopic Survey -- IX. The Clustering
  Environments of an Unbiased Sample of Local AGN
  We characterize the environments of local accreting supermassive black holes
by measuring the clustering of AGN in the Swift/BAT Spectroscopic Survey
(BASS). With 548 AGN in the redshift range 0.01<z<0.1 over the full sky from
the DR1 catalog, BASS provides the largest, least biased sample of local AGN to
date due to its hard X-ray selection (14-195 keV) and rich
multiwavelength/ancillary data. By measuring the projected cross-correlation
function between the AGN and 2MASS galaxies, and interpreting it via halo
occupation distribution (HOD) and subhalo-based models, we constrain the
occupation statistics of the full sample, as well as in bins of absorbing
column density and black hole mass. We find that AGN tend to reside in galaxy
group environments, in agreement with previous studies of AGN throughout a
large range of luminosity and redshift, and that on average they occupy their
dark matter halos similar to inactive galaxies of comparable stellar mass. We
also find evidence that obscured AGN tend to reside in denser environments than
unobscured AGN, even when samples were matched in luminosity, redshift, stellar
mass, and Eddington ratio. We show that this can be explained either by
significantly different halo occupation distributions or statistically
different host halo assembly histories. Lastly, we see that massive black holes
are slightly more likely to reside in central galaxies than black holes of
smaller mass.
