1206.2899 (Charles D. Dermer)

Diffuse Galactic Gamma Rays from Shock-Accelerated Cosmic Rays    [PDF]

Charles D. Dermer

A shock-accelerated particle flux \propto p^-s, where p is the particle momentum, follows from simple theoretical considerations of cosmic-ray acceleration at nonrelativistic shocks followed by rigidity-dependent escape into the Galactic halo. A flux of shock-accelerated cosmic-ray protons with s ~ 2.8 provides a good fit to the Fermi-LAT gamma-ray emission spectra of high-latitude and molecular cloud gas. A break in the spectrum of cosmic-ray protons claimed by Neronov, Semikoz, and Taylor (PRL, 108, 051105, 2012) when fitting the gamma-ray spectra of high-latitude molecular clouds is a consequence of using an unphysical cosmic-ray proton flux described by a power law in kinetic energy.

View original: http://arxiv.org/abs/1206.2899