Observational signatures of particle acceleration in supernova remnants

TL;DR

This paper reviews observational evidence of particle acceleration in supernova remnants and discusses their role as sources of Galactic cosmic rays, including shock processes and energy considerations.

Contribution

It provides a comprehensive summary of multi-wavelength observations and analyzes the acceleration mechanisms and cosmic-ray energy budget in supernova remnants.

Findings

Supernova remnants show signatures of particle acceleration across the electromagnetic spectrum.

Shock modification by cosmic rays affects the shape and maximum energy of the cosmic-ray spectrum.

There are unresolved issues questioning supernova remnants as the primary sources of Galactic cosmic rays.

Abstract

We evaluate the current status of supernova remnants as the sources of Galactic cosmic rays. We summarize observations of supernova remnants, covering the whole electromagnetic spectrum and describe what these obser- vations tell us about the acceleration processes by high Mach number shock fronts. We discuss the shock modification by cosmic rays, the shape and maximum energy of the cosmic-ray spectrum and the total energy budget of cosmic rays in and surrounding supernova remnants. Additionally, we discuss problems with supernova remnants as main sources of Galactic cosmic rays, as well as alternative sources.