%0 Journal Article
%T The radio-loudness dichotomy: environment or black-hole mass?
%A R. J. McLure
%A J. S. Dunlop
%J Physics
%D 2001
%I arXiv
%X The results of a comprehensive study of the cluster environments and black-hole masses of an optically matched sample of radio-loud and radio-quiet quasars are presented. No evidence is found for a difference in large-scale environments, with both quasar classes found to be located in clusters of Abell class $\sim0$ . Conversely, virial black-hole mass estimates based on H$_{\beta}$ line-widths show a clear difference in the quasar black-hole mass distributions. Our results suggest that a black-hole mass of $\sim10^{9}\Msolar$ is required to produce a powerful radio-loud quasar, and that it is black-hole mass and accretion rate which hold the key to the radio-loudness dichotomy.
%U http://arxiv.org/abs/astro-ph/0102166v1