Status of Ground-based and Galactic Gamma-ray Astronomy

TL;DR

This paper reviews recent advances in ground-based and space-based gamma-ray astronomy, highlighting progress in identifying cosmic ray accelerators, studying particle escape, and detecting gamma-ray transients, especially in Galactic contexts.

Contribution

It provides a comprehensive overview of recent developments in gamma-ray astronomy, emphasizing Galactic observations and the progress made in understanding high-energy cosmic phenomena.

Findings

Identification of PeVatrons as cosmic ray sources

Detection of gamma-ray transients like gamma-ray bursts

Insights into particle escape mechanisms from accelerators

Abstract

This conference proceedings is a write-up of the Gamma-ray Indirect rapporteur talk given at the 37th International Cosmic Ray Conference (ICRC 2021). In contrast to previous ICRCs, this years edition was held in a fully virtual format, with dedicated discussion sessions organised around specific scientific themes. Many of these topics span the two categories of Gamma-ray Indirect (GAI) and Gamma-ray Direct (GAD), observations of gamma-rays by ground-based and space-based facilities respectively. To cover this organisation by topic in a coherent manner, this GAI rapporteur contribution focuses predominantly (but not exclusively) on Galactic gamma-ray astronomy, whereas the GAD rapporteur contribution focuses predominantly (but not exclusively) on Extra-galactic gamma-ray astronomy. In recent years, the field has seen enormous progress in both theory and observation, particularly in identifying PeVatrons (accelerators of Cosmic Rays to PeV energies), studies of particle escape from the accelerator, and detection of gamma-ray transients, especially gamma-ray bursts.