AGN as cosmic thermostats
  We present a simple analytical model and the results of numerical simulations supporting the idea of periodical heating of cluster gas by AGN outflows. We show why, under this assumption, we are extremely unlikely to observe clusters containing gas with a temperature below about 1 keV. We review the results from numerical hydro-simulations studying the mechanisms by which AGN outflows heat the cluster gas. 
Christian R. Kaiser (1), Marcus Brueggen (2), James J. Binney (3) ((1)   Southampton University, (2) International Universit...