AGN and galactic sites of cosmic ray origin

Abstract

We review recent progress in our understanding of the physics of energetic particles in our Galaxy, in active galaxies such as starburst galaxies, in active galactic nuclei and in the jets and radio hot spots of powerful radio galaxies and radioloud quasars. We propose that cosmic rays originate mainly in three sites, a) normal supernova explosions into the approximately homogeneous interstellar medium, b) supernova explosions into stellar winds, and c) hot spots of powerful radio galaxies. The predictions based on this proposition have been tested successfully against airshower data over the particle energy range from 10 TeV to 100 EeV. The low energy cosmic ray particles carried out by galactic winds to the intergalactic medium may ionize and heat this medium consistent with all known constraints. Furthermore we propose that radioloud quasars accelerate nuclei to high energies in shocks in the inner sections of their jets, and thus initiate hadronic cascades which produce the $γ$-ray emission observed with GRO. Radio observations of the Galactic center compact source suggest that there is a jet similar to that in quasars, but very much weaker in its emission; simple modelling suggests that the power carried by this jet is of order similar to the accretion disk luminosity. By analogy we speculate that also radioweak quasars have jets which carry a large proportion of the accretion power, and which accelerate particles to high energy.