Very-High Energy Gamma-Ray Flux Limits for Nearby Active Galactic Nuclei

TL;DR

This paper reports on H.E.S.S. observations that set upper limits on very-high energy gamma-ray fluxes from 63 nearby active galactic nuclei, leveraging a large, unbiased sky sample to study extragalactic source populations.

Contribution

It provides the first comprehensive flux limits for a broad sample of nearby AGN using H.E.S.S. data, including regions outside targeted sources.

Findings

No significant gamma-ray emission detected from the AGN sample.

Established upper flux limits for each AGN in the sample.

Results inform models of gamma-ray emission in nearby active galaxies.

Abstract

Combining the results of targeted observations, H.E.S.S. has accumulated a large amount of extra-galactic exposure at TeV energies. Due to its large field of view a considerable part of the sky (0.6 sr) has been observed with high sensitivity outside the targeted observation positions. Since this exposure region contains little inherent bias, it is well suited for studies of extra-galactic source populations. Given the correlation between ultra-high energy cosmic rays and nearby extra-galactic objects recently claimed by the Auger collaboration, this unbiased sky sample by H.E.S.S. is of interest since it includes (besides the targeted sources) 63 AGN within 100 Mpc, for which very-high energy gamma-ray flux limits are derived.