Galactic Propagation of Cosmic Rays from Individual Supernova Remnants

TL;DR

This paper models how cosmic rays from individual supernova remnants propagate through the Galaxy, using gamma-ray data to infer source spectra and the GALPROP code for propagation, to understand their contribution to observed cosmic rays.

Contribution

It combines gamma-ray observations with cosmic ray propagation modeling to quantify the SNRs' contribution to galactic cosmic rays for the first time.

Findings

SNRs significantly contribute to cosmic rays up to PeV energies.

Propagation effects shape the observed cosmic ray spectrum.

Results inform models of galactic cosmic ray origins.

Abstract

It is widely believed that supernova remnants are the best candidate sources for the observed cosmic ray flux up to the knee, i.e. up to ~PeV energies. Indeed, the gamma-ray spectra of some supernova remnants can be well explained by assuming the decay of neutral pions which are created in hadronic interactions. Therefore, fitting the corresponding gamma spectra allows us to derive the spectra of cosmic rays at the source which are locally injected into our Galaxy. Using these spectra as a starting point, we propagate the cosmic rays through the Galaxy using the publicly available GALPROP code. Here, we will present first results on the contribution of those SNRs to the total cosmic ray flux and discuss implications.