High-Energy Cosmic Rays from Supernovae

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 ∼ 1017 eV, cosmic rays are believed to be produced in the Milky Way, while above that energy, their origin is probably extragalactic. In the early 1930s, supernovae were already identified as possible sources for the galactic component of cosmic rays. After the 1970s this idea has gained more and more credibility, thanks to the development of the diffusive shock acceleration theory, which provides a robust theoretical framework for particle energization in astrophysical environments. Afterward, 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 nonlinear 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.