Gamma ray emission and stochastic particle acceleration in galaxy clusters

Abstract

FERMI (formely GLAST) will shortly provide crucial information on relativistic particles in galaxy clusters. We discuss non thermal emission in the context of general calculations in which relativistic particles (protons and secondary electrons due to proton‐proton collisions) interact with MHD turbulence generated in the cluster volume during cluster mergers. Diffuse cluster‐scale radio emission (Radio Halos) and hard X‐rays are produced during massive mergers while gamma ray emission, at some level, is expected to be common in galaxy clusters.