Gamma-ray emission from the black hole's vicinity in AGN

TL;DR

This paper discusses how magnetospheric gaps near supermassive black holes could produce variable gamma-ray emission, providing insights into extreme environments around black holes, with implications for observations of radio galaxies like Cen A, M87, and IC310.

Contribution

It highlights the potential of magnetospheric gap models to explain gamma-ray variability and discusses constraints on gap sizes based on rapid variability observations.

Findings

Magnetospheric gaps can produce variable gamma-ray emission.

Rapid variability constrains gap sizes and powers.

Implications for observations of Cen A, M87, and IC310.

Abstract

Non-thermal magnetospheric processes in the vicinity of supermassive black holes have attracted particular attention in recent times. Gap-type particle acceleration accompanied by curvature and Inverse Compton radiation could in principle lead to variable gamma-ray emission that may be detectable with current instruments. We shortly comment on the occurrence of magnetospheric gaps and the realisation of different potentials. The detection of rapid variability becomes most instructive by imposing a constraint on possible gap sizes, thereby limiting extractable gap powers and allowing to assess the plausibility of a magnetospheric origin. The relevance of this is discussed for the radio galaxies Cen A, M87 and IC310. The detection of magnetospheric gamma-ray emission generally allows for a sensitive probe of the near-black-hole region and is thus of prime interest for advancing our understanding of the (astro)physics of extreme environments