MERGERS OF SUPERMASSIVE BLACK HOLES IN ASTROPHYSICAL ENVIRONMENTS

Abstract

Modeling the late inspiral and merger of supermassive black holes is central
\nto understanding accretion processes and the conditions under which
\nelectromagnetic emission accompanies gravitational waves. We use fully general
\nrelativistic, hydrodynamics simulations to investigate how electromagnetic
\nsignatures correlate with black hole spins, mass ratios, and the gaseous
\nenvironment in this final phase of binary evolution. In all scenarios, we find
\nsome form of characteristic electromagnetic variability whose pattern depends
\non the spins and binary mass ratios. Binaries in hot accretion flows exhibit a
\nflare followed by a sudden drop in luminosity associated with the plunge and
\nmerger, as well as quasi-periodic oscillations correlated with the
\ngravitational waves during the inspiral. Conversely, circumbinary disk systems
\nare characterized by a low luminosity of variable emission, suggesting
\nchallenging prospects for their detection.
\n