Nonthermal processes and particle acceleration in supernova remnants

TL;DR

This paper reviews how supernova remnant shocks accelerate particles to high energies, discusses the mechanisms involved, and examines observational evidence of nonthermal emissions to understand their role in cosmic-ray origins.

Contribution

It provides a comprehensive overview of particle acceleration mechanisms in SNRs and analyzes recent observational data related to nonthermal emissions.

Findings

SNR shocks can accelerate particles up to 100 TeV.

Observations of X-ray and gamma-ray emissions support SNRs as cosmic-ray sources.

The paper discusses the potential of SNRs to reach the cosmic-ray knee energy.

Abstract

Shocks of supernova remnants (SNRs) accelerate charged particles up to 100 TeV range via diffusive shock acceleration (DSA) mechanism. It is believed that shocks of SNRs are the main contributors to the pool of Galactic cosmic rays, although it is still under debate whether they can accelerate particles up to the "knee" energy (10^15.5 eV) or not. In this chapter, we start with introducing SNRs as likely sources of cosmic rays and the radiation mechanisms associated with cosmic rays (section 3). In the section 4, we summarize the mechanism for particle acceleration, including basic diffusive shock acceleration and nonlinear effects, as well as discussing the injection problem. Section 5 is devoted to the X-ray and gamma-ray observations of nonthermal emission from SNRs, and what these reveal about the cosmic-ray acceleration properties of SNRs.