2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/220371FERMI (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.4 pages, 2 Figure, proc. of the 4th Heidelberg International Symposium on High Energy Gamma-ray AstronomyAstrophysicstext