  Several phenomena in high energy astrophysics have been recently related to
clusters of galaxies and to cosmic ray interactions occurring inside these
structures. In many of these phenomena the observable effects depend on the
energy density of cosmic rays confined in the Intra Cluster (IC) medium, which
is a poorly known quantity. We propose here that useful indications about this
quantity can be obtained from present and future observations of galaxy
clusters in the radio and hard X-ray frequency ranges.
