A Very-High-Energy Gamma-Ray View of the Transient Sky

TL;DR

This review discusses recent advances in very-high-energy gamma-ray astronomy, focusing on transient phenomena like novae, supernovae, and fast radio bursts, highlighting their physical mechanisms and future observational prospects.

Contribution

It provides a comprehensive overview of the current state of VHE transient observations and discusses future expectations for the field.

Findings

Identification of key transient sources in VHE gamma-ray astronomy

Insights into physical processes like cosmic-ray acceleration and magnetic reconnection

Future facilities are expected to enhance transient detection capabilities

Abstract

The development of the latest generation of Imaging Atmospheric Cherenkov Telescopes (IACTs) over recent decades has led to the discovery of new extreme astrophysical phenomena in the very-high-energy (VHE, E > 100 GeV) gamma-ray regime. Time-domain and multi-messenger astronomy are inevitably connected to the physics of transient VHE emitters, which show unexpected (and mostly unpredictable) flaring or exploding episodes at different timescales. These transients often share the physical processes responsible for the production of the gamma-ray emission, through cosmic-ray acceleration, magnetic reconnection, jet production and/or outflows, and shocks interactions. In this review, we present an up-to-date overview of the VHE transients field, spanning from novae to supernovae, neutrino counterparts or fast radio bursts, among others, and we outline the expectations for future facilities.