The cluster environments of powerful radio-loud and radio-quiet AGN

Abstract

The spatial clustering amplitude (B_{gq}) is determined for a sample of 44 powerful AGN at z~0.2. No significant difference is detected in the richness of the cluster environments of the radio-loud and radio-quiet sub-samples, both of which typically inhabit environments as rich as Abell Class ~0. Comparison with radio luminosity-matched samples from Hill & Lilly (1991) and Wold et al. (2000a) suggests that there is no epoch-dependent change in environment richness out to at least z>=0.5 for either radio galaxies or radio quasars. Comparison with the APM cluster survey shows that, contrary to current folklore, powerful AGN do not avoid rich clusters, but rather display a spread in cluster environment which is perfectly consistent with being drawn at random from the massive elliptical population. Finally, we argue that virtually all Abell class ~0 clusters contained an active galaxy during the epoch of peak quasar activity at z~2.5.