A search for Very High Energy gamma-ray emission from Passive Super-massive Black Holes

TL;DR

This paper investigates the potential for very high energy gamma-ray emission from passive super-massive black holes, specifically analyzing H.E.S.S. observations of NGC 1399, and discusses constraints on emission mechanisms.

Contribution

It presents the first observational constraints on VHE gamma-ray emission from a passive SMBH, expanding understanding of black hole emission processes beyond active systems.

Findings

No VHE gamma-ray signal detected from NGC 1399

Constraints on emission models are established

Passive SMBHs may not be significant VHE gamma-ray sources

Abstract

Jets of Active Galactic Nuclei (AGN) are established emitters of very high energy (VHE; >100 GeV) gamma-rays. VHE radiation is also expected to be emitted from the vicinity of super-massive black holes (SMBH), irrespective of their activity state. Accreting SMBH rotate and generate a dipolar magnetic field. In the magnetosphere of the spinning black hole, acceleration of particles can take place in the field gaps. VHE emission from these particles is feasible via leptonic or hadronic processes. Therefore quiescent systems, where the lack of a strong photon field allows the VHE emission to escape, are candidates for emission. The H.E.S.S. experiment has observed the passive SMBH in the nearby galaxy NGC 1399. No VHE gamma-ray signal is observed from the galactic nucleus. Constraints set by the NGC 1399 observations are discussed in the context of different mechanisms for the production of VHE gamma-ray emission.