Feedback from radio-loud AGN

The evidence for direct interactions between radio-loud active galactic nuclei (AGN) and their surrounding gas is reviewed. New results from the Sloan Digital Sky Survey provide insightful information on the origin of radio-loud AGN activity, and allow study of the energetic influence of the radio-loud AGN on their surroundings, and the consequences of this for the accretion of gas onto elliptical galaxies. These results show that recurrent radio-loud AGN activity may provide a self-regulating feedback mechanism capable of controlling the rate of growth of galaxies. Finally, the effect of radio-loud AGN activity on gas at the scales of galaxy clusters is discussed. (c) 2006 Elsevier B.V. All rights reserved.