A Multi-Wavelength Photometric Census of AGN and Star Formation Activity
  in the Brightest Cluster Galaxies of X-ray Selected Clusters
  Despite their reputation as being "red and dead", the unique environment
inhabited by Brightest Cluster Galaxies (BCGs) can often lead to a
self-regulated feedback cycle between radiatively cooling intracluster gas and
star formation and AGN activity in the BCG. However the prevalence of "active"
BCGs, and details of the feedback involved, are still uncertain. We have
performed an optical, UV and Mid-IR photometric analysis of the BCGs in 981
clusters at 0.03 < z < 0.5, selected from the ROSAT All Sky Survey. Using
Pan-STARRS PS1 3pi, GALEX and WISE survey data we look for BCGs with
photometric colours which deviate from that of the bulk population of passive
BCGs - indicative of AGN and/or star formation activity within the BCG. We find
that whilst the majority of BCGs are consistent with being passive, at least
14% of our BCGs show a significant colour offset from passivity in at least one
colour index. And, where available, supplementary spectroscopy reveals the
majority of these particular BCGs show strong optical emission lines. On
comparing BCG "activity" with the X-ray luminosity of the host cluster, we find
that BCGs showing a colour offset are preferentially found in the more X-ray
luminous clusters, indicative of the connection between BCG "activity" and the
intracluster medium.
