Cosmic rays, cooling flows and non-thermal processes in galaxy clusters

Bremsstrahlung cooling of the intracluster (IC) plasma in galaxy clusters can be quenched by the energy supplied to the plasma by hadronic cosmic rays (CRs). This solution requires an energy deposition more intense and more distributed than in conventional CR models, but this alternative model is also successful in describing the origin of CRs. The model also provides a simple explanation of other puzzling features of galaxy clusters, among which we discuss here the non-thermal tail of their X-ray emission spectrum.