High energy cosmic photons and neutrinos

Open Access
Publisher Website
Google Scholar
Abstract
This review concentrates primarily on the problem of interpreting the recent X-ray and γ-ray observations of celestial sources. The expected fluxes of hard radiation from various processes are estimated (when possible) and are compared with the observations. We compute the synchrotron, bremsstrahlung, and (inverse) Compton spectra originating from relativistic electrons produced (via meson production) in the galaxy and intergalactic medium by cosmic ray nuclear collisions; the spectra from π°-decay are also computed. Neutron stars, stellar coronae, and supernova remnants are reviewed as possible X-ray sources. Special consideration is given to the processes in the Crab Nebula. Extragalactic objects as discrete sources of energetic photons are considered on the basis of energy requirements; special emphasis is given to the strong radio sources and the possibility of the emission of hard radiation during their formation. The problem of the detection of cosmic neutrinos is reviewed. As yet, no definite process can be identified with any of the observed fluxes of hard radiation, although a number of relevant conclusions can be drawn on the basis of the available preliminary observational results. In particular, some cosmogonical theories can be tested.