High Energy Cosmic Rays From Supernovae

TL;DR

This paper reviews the evidence and theory supporting supernova remnants as the primary sources of Galactic cosmic rays, highlighting the acceleration mechanisms, nonlinear effects, and observational support.

Contribution

It consolidates recent observational and theoretical developments that establish supernova remnants as effective accelerators of cosmic rays within the Galaxy.

Findings

Supernova remnants are confirmed as key sources of Galactic cosmic rays.

Diffusive shock acceleration theory explains particle energization in supernovae.

Observational data supports supernova remnants as cosmic ray factories.

Abstract

Cosmic rays are charged relativistic particles that reach the Earth with extremely high energies, providing striking evidence of the existence of effective accelerators in the Universe. Below an energy around $\sim 10^{17}$ eV cosmic rays are believed to be produced in the Milky Way while above that energy their origin is probably extragalactic. In the early '30s supernovae were already identified as possible sources for the Galactic component of cosmic rays. After the '70s this idea has gained more and more credibility thanks to the the development of the diffusive shock acceleration theory, which provides a robust theoretical framework for particle energization in astrophysical environments. Afterwards, mostly in recent years, much observational evidence has been gathered in support of this framework, converting a speculative idea in a real paradigm. In this Chapter the basic pillars of this paradigm will be illustrated. This includes the acceleration mechanism, the non linear effects produced by accelerated particles onto the shock dynamics needed to reach the highest energies, the escape process from the sources and the transportation of cosmic rays through the Galaxy. The theoretical picture will be corroborated by discussing several observations which support the idea that supernova remnants are effective cosmic ray factories.