Abstract:
For a long time black holes (BHs) existed only in theorists’ minds. Now it is well known that all galaxies, including our Milky Way, have a supermassive black hole (SMBH; 10^6-10^9 solar mass) at their centers. Because of strong gravity, BHs are very efficient sources of energy. Even a small fraction of this energy, if absorbed by the host galaxy, can control its star formation. I will discuss the role of the central SMBHs in galaxy formation, focussing on massive galaxies at the centers of galaxy clusters, where the observational evidence is the most convincing. I will discuss recent multiwavelength observations of cluster cores, and present interpretation in terms of a model in which energetic jets powered by SMBHs maintain the plasma in cluster cores in rough thermal balance.