Variability of VHE $\gamma$-ray sources

TL;DR

This paper investigates the variability of very high energy gamma-ray emissions from active galactic nuclei using Cherenkov telescope data, revealing some sources exhibit significant temporal fluctuations in their gamma-ray intensity.

Contribution

It introduces a simple method to analyze gamma-ray variability based solely on source and background event counts, providing new insights into AGN emission stability.

Findings

Detected variability in gamma-ray signals from AGNs.

Identified instances of excess and deficient source events.

Highlighted the importance of monitoring gamma-ray flux over time.

Abstract

We study changes in the $\gamma$-ray intensity at very high energies observed from selected active galactic nuclei. Publicly available data collected by Cherenkov telescopes were examined by means of a simple method utilizing solely the number of source and background events. Our results point to some degree of time variability in signal observed from the investigated sources. Several measurements were found to be excessive or deficient in the number of source events when compared to the source intensity deduced from other observations.