Close encounters of three black holes

TL;DR

This paper presents the first long-term fully relativistic simulations of three equal-mass black holes, revealing complex merger dynamics, distinctive gravitational waveforms, and energy redistribution effects not seen in binary systems.

Contribution

It introduces the first detailed numerical evolutions of three black holes in close orbit, highlighting new dynamical behaviors and gravitational wave signatures.

Findings

Complex trajectories and energy redistribution observed.

Binary disruption and rapid mergers in one configuration.

Formation of a highly elliptical binary with minimal inspiral.

Abstract

We present the first fully relativistic longterm numerical evolutions of three equal-mass black holes in a system consisting of a third black hole in a close orbit about a black-hole binary. We find that these close-three-black-hole systems have very different merger dynamics from black-hole binaries. In particular, we see complex trajectories, a redistribution of energy that can impart substantial kicks to one of the holes, distinctive waveforms, and suppression of the emitted gravitational radiation. We evolve two such configurations and find very different behaviors. In one configuration the binary is quickly disrupted and the individual holes follow complicated trajectories and merge with the third hole in rapid succession, while in the other, the binary completes a half-orbit before the initial merger of one of the members with the third black hole, and the resulting two-black-hole system forms a highly elliptical, well separated binary that shows no significant inspiral for (at least) the first t~1000M of evolution.