Black hole fusion in the extreme mass ratio limit

TL;DR

This paper develops a precise method to construct event horizons during the merger of a small rotating black hole with a much larger one, revealing new topological phenomena and confirming a conjecture on critical exponents.

Contribution

It introduces a simple, accurate approach for modeling black hole mergers in the extreme mass ratio limit, including topology changes and critical behavior analysis.

Findings

Successful construction of event horizons for black hole mergers with arbitrary spins.

Discovery of transient toroidal topology during the merger process.

Proof of a conjecture on universal critical exponents in horizon pinch scenarios.

Abstract

We present a simple, general, and accurate construction of the event horizons for the fusion of two neutral, rotating black holes with arbitrary orientation and values of their spins, in the extreme mass ratio limit where one black hole is much larger than the other. We compute several parameters that characterize the fusion and investigate their dependence on the black hole spin and orientation axis. We also exhibit and study the appearance of transient toroidal topology of the horizon. An earlier conjecture about universal critical exponents before and after an axisymmetric pinch is proven.