Search for high energy $\gamma$-rays from the direction of the candidate electromagnetic counterpart to the binary black hole merger gravitational-wave event S190521g

TL;DR

This study searched for high-energy gamma-ray emission from the candidate electromagnetic counterpart of the S190521g black hole merger event using Fermi-LAT data, but found no significant signal, providing upper limits and discussing implications for cosmic ray and neutrino production.

Contribution

First search for high-energy gamma rays from the electromagnetic counterpart of S190521g using Fermi-LAT data, setting upper limits and exploring astrophysical implications.

Findings

No significant gamma-ray signal detected.

Established upper limits on gamma-ray emission.

Discussed relevance to cosmic ray and neutrino sources.

Abstract

The gravitational-wave event S190521g -- a likely binary black hole merger in the accretion disk of an active galactic nucleus -- was accompanied by an optical counterpart. Such dense environments around luminous energy release regions are favourable for high energy $\gamma$-ray production. We report on a search for high energy $\gamma$-rays from the direction of the candidate electromagnetic counterpart to the S190521g event using publicly-available data of the Fermi-LAT space $\gamma$-ray telescope. No significant signal was found. We present upper limits on the spectral energy distribution of the source in the 100 MeV - 300 GeV energy range. We discuss the importance of studying S190521g-like transients in the context of cosmic ray acceleration, $\gamma$-ray and neutrino production in such sources.