Supernova Remnants in Gamma Rays

TL;DR

This paper reviews gamma-ray observations of supernova remnants, discussing their role as cosmic ray accelerators and highlighting the complex phenomenology observed, which challenges standard models.

Contribution

It provides a comprehensive review of gamma-ray observations of SNRs and discusses future prospects in understanding their role in cosmic ray acceleration.

Findings

Detection of gamma-ray emission from several SNRs at GeV and TeV energies.

Complex phenomenology observed challenges standard DSA models.

SNRs are confirmed as efficient electron and proton accelerators.

Abstract

In the 1960s, the remnants of supernova explosions (SNRs) were indicated as a possible source of galactic cosmic rays through the Diffusive Shock Acceleration (DSA) mechanism. Since then, the observation of gamma-ray emission from relativistic ions in these objects has been one of the main goals of high-energy astrophysics. A few dozen SNRs have been detected at GeV and TeV photon energies in the last two decades. However, these observations have shown a complex phenomenology that is not easy to reduce to the standard paradigm based on DSA acceleration. Although the understanding of these objects has greatly increased, and their nature as efficient electron and proton accelerators has been observed, it remains to be clarified whether these objects are the main contributors to galactic cosmic rays. Here, we review the observations of {\gamma}-ray emission from SNRs and the perspectives for the future.