Radio Galaxies at VHE energies

TL;DR

This review summarizes the observed properties of radio galaxies at very high gamma-ray energies, highlighting their unique features and discussing the physical mechanisms behind their VHE emissions, including recent advances in black hole gap physics.

Contribution

It provides a comprehensive overview of radio galaxies at VHE energies and discusses new insights into their emission mechanisms, especially related to black hole gap physics.

Findings

Radio galaxies exhibit unique gamma-ray spectra and ultrafast VHE variability.

Recent developments in black hole gap physics help explain VHE emission origins.

Radio galaxies serve as key probes for understanding AGN physics at high energies.

Abstract

Radio Galaxies have by now emerged as a new $\gamma$-ray emitting source class on the extragalactic sky. Given their remarkable observed characteristics, such as unusual gamma-ray spectra or ultrafast VHE variability, they represent unique examples to probe into the nature and physics of AGN in general. This review provides a compact summary of their observed characteristics at very high $\gamma$-ray energies (VHE; $> 100$ GeV) along with a discussion of their possible physics implications. A particular focus is given to a concise overview of fundamental concepts concerning the origin of variable VHE emission, including recent developments in black hole gap physics.