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

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 favorable for high energy γ-ray production. We report on a search for high energy γ-rays from the direction of the candidate electromagnetic counterpart to the S190521g event using publicly-available data of the Fermi-LAT space γ-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, γ-ray and neutrino production in such sources.