X-ray bright active galactic nuclei in massive galaxy clusters - II. The fraction of galaxies hosting active nuclei

We present a measurement of the fraction of cluster galaxies hosting X-ray bright active galactic nuclei (AGN) as a function of clustercentric distance scaled in units of r(500). Our analysis employs high-quality Chandra X-ray and Subaru optical imaging for 42 massive X-ray-selected galaxy cluster fields spanning the redshift range 0.2 < z < 0.7. In total, our study involves 176 AGN with bright (R < 23) optical counterparts above a 0.5-8.0 keV flux limit of 10(-14) erg cm(-2) s(-1). When excluding central dominant galaxies from the calculation, we measure a cluster galaxy AGN fraction in the central regions of the clusters that is similar to 3 times lower than the field value. This fraction increases with clustercentric distance before becoming consistent with the field at similar to 2.5r(500). Our data exhibit similar radial trends to those observed for star formation and optically selected AGN in cluster member galaxies, both of which are also suppressed near cluster centres to a comparable extent. These results strongly support the idea that X-ray AGN activity and strong star formation are linked through their common dependence on available reservoirs of cold gas.