Probing General Relativity With Mergers of Supermassive and Intermediate-Mass Black Holes

TL;DR

This paper explores the potential of future gravitational wave detectors to observe mergers between intermediate-mass and supermassive black holes, providing insights into black hole physics and galaxy evolution.

Contribution

It analyzes the astrophysical processes of black hole mergers and discusses how gravitational wave signals can reveal spacetime geometry of rotating black holes.

Findings

High signal-to-noise ratio detections possible with space-based detectors

End-of-inspiral signals can be analyzed without matched filtering

Potential to test spacetime geometry of rotating black holes

Abstract

Recent observations and stellar dynamics simulations suggest that thousand solar mass black holes can form in compact massive young star clusters. Any such clusters in the bulge of their host galaxy will spiral to the center within a few hundred million years, where their intermediate-mass black holes are likely to merge eventually with the galaxy's supermassive black hole. If such mergers are common, then future space-based gravitational wave detectors such as the Laser Interferometer Space Antenna will detect them with such a high signal to noise ratio that towards the end of the inspiral the orbits will be visible in a simple power density spectrum, without the need for matched filtering. We discuss the astrophysics of the inspiral of clusters in the nuclear region of a galaxy and the subsequent merger of intermediate-mass with supermassive black holes. We also examine the prospects for understanding the spacetime geometry of rotating black holes, based on phase connection of the strong signals visible near the end of these extreme mass ratio inspirals.