Self-Similar Perturbation of an Accretion Disc around Merging Black Holes

Abstract

We study the possibility that merging of a binary black hole surrounded by a circumbinary accretion disc may produce an electromagnetic response. When black holes are merging, the mass of a target object decreases due to radiating gravitational waves; and, consequently, the disc experiences perturbations, which manifest themselves in, among other phenomena, producing rather intense shock waves. Based on the numerical modeling results, we analyze the self-similar solution that describes the evolution of a perturbed accretion disc while accounting for the vertical expansion effect leading to the adiabatic cooling of matter heated by shock waves. The methodology developed allows us to correctly estimate the magnitude of the heating of matter caused by shock waves and, consequently, to determine parameters of the electromagnetic radiation produced by the disc, including the light curve, the radiation spectrum, and the outburst duration.