The γ-ray and neutrino background and cosmic chemical evolution

Abstract

The global star formation history of the universe and the associated supernova rate are now reasonably well known. Core collapse supernovae are copious sources of neutrinos, and produce an integrated neutrino flux at Earth of ∼10 neutrinos/cm2 s for each flavor. While terrestrial and extraterrestrial neutrino backgrounds exceed the supernova flux below ∼15 MeV and above ∼40 MeV, in the intermediate band the neutrino background from Type II/Ib supernovae may be detectable. Similarly, Type Ia supernovae produce the bulk of the extragalactic γ-ray background in the MeV range, while blazars dominate at higher energies and Seyfert galaxies at lower energies. The γ-ray and neutrino background probe cosmic chemical evolution.