Merging and Clustering of the Swift BAT AGN Sample
  We discuss the merger rate, close galaxy environment, and clustering on
scales up to a Mpc of the SWIFT BAT hard X-ray sample of nearby (z<0.05),
moderate-luminosity active galactic nuclei (AGN). We find a higher incidence of
galaxies with signs of disruption compared to a matched control sample (18%
versus 1%) and of close pairs within 30 kpc (24% versus 1%). We also find a
larger fraction with companions compared to normal galaxies and optical
emission line selected AGN at scales up to 250 kpc. We hypothesize that these
merging AGN may not be identified using optical emission line diagnostics
because of optical extinction and dilution by star formation. In support of
this hypothesis, in merging systems we find a higher hard X-ray to [OIII] flux
ratio, as well as emission line diagnostics characteristic of composite or
star-forming galaxies, and a larger IRAS 60 um to stellar mass ratio.
