A Multi-wavelength Survey of AGN in Massive Clusters: AGN Detection and
  Cluster AGN Fraction
  We aim to study the effect of environment on the presence and fuelling of
Active Galactic Nuclei (AGN) in massive galaxy clusters. We explore the use of
different AGN detection techniques with the goal of selecting AGN across a
broad range of luminosities, AGN/host galaxy flux ratios, and obscuration
levels. From a sample of 12 galaxy clusters at redshifts 0.5 < z < 0.9, we
identify AGN candidates using optical variability from multi-epoch HST imaging,
X-ray point sources in Chandra images, and mid-IR SED power-law fits through
the Spitzer IRAC channels. We find 178 optical variables, 74 X-ray point
sources, and 64 IR power law sources, resulting in an average of ~25 AGN per
cluster. We find no significant difference between the fraction of AGN among
galaxies in clusters and the percentage of similarly-detected AGN in field
galaxy studies (~2.5%). This result provides evidence that galaxies are still
able to fuel accretion onto their supermassive black holes, even in dense
environments. We also investigate correlations between the percentage of AGN
and cluster physical properties such as mass, X-ray luminosity, size,
morphology class and redshift. We find no significant correlations among
cluster properties and the percentage of AGN detected.
