The Role of Host Galaxy for the Environmental Dependence of Active
  Nuclei in Local Galaxies
  We discuss the environment of local hard X-ray selected active galaxies, with
reference to two independent group catalogues. We find that the fraction of
these AGN in S0 host galaxies decreases strongly as a function of galaxy group
size (halo mass) - which contrasts with the increasing fraction of galaxies of
S0 type in denser environments. However, there is no evidence for an
environmental dependence of AGN in spiral galaxies. Because most AGN are found
in spiral galaxies, this dilutes the signature of environmental dependence for
the population as a whole. We argue that the differing results for AGN in
disk-dominated and bulge-dominated galaxies is related to the source of the gas
fuelling the AGN, and so may also impact the luminosity function, duty cycle,
and obscuration. We find that there is a significant difference in the
luminosity function for AGN in spiral and S0 galaxies, and tentative evidence
for some difference in the fraction of obscured AGN.
