Interactions of Cosmic Ray Nuclei

TL;DR

This paper provides formulas for cosmic ray nuclei energy losses, derives their equilibrium spectra in galaxies, and discusses a spectral break at 450 MeV related to different cooling processes, with implications for gamma-ray background origins.

Contribution

It introduces comprehensive formulas for cosmic ray nuclei energy losses and applies them to model their spectra across various galaxy types, highlighting a universal spectral break at 450 MeV.

Findings

Spectral break at 450 MeV independent of matter density

Transition from Coulomb/ionization to pion production losses

Implications for cosmic gamma ray background

Abstract

We present convenient formulae for the energy losses of energetic atomic nuclei over the entire energy range relevant to the physics of cosmic rays. Results are applied to a leaky-box equation with a complete loss term. Thereby we derive the equilibrium spectrum of cosmic rays in various types of galaxies. We emphasize a spectral break energy at 450 MeV independent of the matter density, resulting from the transition from Coulomb and ionization losses to pion production losses as the relevant cooling process for the cosmic ray nuclei . We comment on the possible cosmic ray origin of the cosmic gamma ray background.