A Multi-Wavelength Study of Low Redshift Clusters of Galaxies I.
  Comparison of X-ray and Mid-Infrared Selected AGNs
  Clusters of galaxies have long been used as laboratories for the study of
galaxy evolution, but despite intense, recent interest in feedback between AGNs
and their hosts, the impact of environment on these relationships remains
poorly constrained. We present results from a study of AGNs and their host
galaxies found in low-redshift galaxy clusters. We fit model spectral energy
distributions (SEDs) to the combined visible and mid-infrared (MIR) photometry
of cluster members and use these model SEDs to determine stellar masses and
star-formation rates (SFRs). We identify two populations of AGNs, the first
based on their X-ray luminosities (X-ray AGNs) and the second based on the
presence of a significant AGN component in their model SEDs (IR AGNs). We find
that the two AGN populations are nearly disjoint; only 8 out of 44 AGNs are
identified with both techniques. We further find that IR AGNs are hosted by
galaxies with similar masses and SFRs but higher specific SFRs (sSFRs) than
X-ray AGN hosts. The relationship between AGN accretion and host star-formation
in cluster AGN hosts shows no significant difference compared to the
relationship between field AGNs and their hosts. The projected radial
distributions of both AGN populations are consistent with the distribution of
other cluster members. We argue that the apparent dichotomy between X-ray and
IR AGNs can be understood as a combination of differing extinction due to cold
gas in the host galaxies of the two classes of AGNs and the presence of weak
star-formation in X-ray AGN hosts.
