Fluxes of diffuse gamma rays and neutrinos from cosmic-ray interactions with circumgalactic gas

TL;DR

This paper analyzes gamma-ray and neutrino fluxes from cosmic-ray interactions with the Milky Way's circumgalactic gas and other galaxies, finding neutrinos are insufficient for IceCube signals but gamma-ray contributions are notable.

Contribution

It provides a quantitative assessment of diffuse gamma-ray and neutrino fluxes from galactic and extragalactic circumgalactic gas interactions.

Findings

Neutrino flux from the Milky Way's corona is too low to explain IceCube observations.

Gamma-ray flux contribution from circumgalactic gas is significant for diffuse gamma-ray background.

The combined effect of other galaxies' coronae adds to the overall gamma-ray flux.

Abstract

The Milky Way is surrounded by a gravitationally bound gas corona extending up to the Galaxy's virial radius. Interactions of cosmic-ray particles with this gas give rise to energetic secondary gamma rays and neutrinos. We present a quantitative analysis of the neutrino and gamma-ray fluxes from the corona of the Milky Way together with a combined contribution of coronae of other galaxies. The high-energy neutrino flux is insufficient to explain the IceCube results, while the contribution to the FERMI-LAT diffuse gamma-ray flux is not negligible.