Simulating merging binary black holes with nearly extremal spins

TL;DR

This paper presents the first successful numerical simulations of merging binary black holes with nearly extremal spins, surpassing previous spin limits and enabling new exploration of black hole dynamics.

Contribution

The authors develop an improved initial-data method to simulate nearly extremal black hole mergers, overcoming the previous spin limit of 0.93.

Findings

Simulated black holes with spins of 0.95, nearly extremal.

Successfully modeled 12.5 orbits before merger.

Enabled future studies of high-spin black hole dynamics.

Abstract

Astrophysically realistic black holes may have spins that are nearly extremal (i.e., close to 1 in dimensionless units). Numerical simulations of binary black holes are important tools both for calibrating analytical templates for gravitational-wave detection and for exploring the nonlinear dynamics of curved spacetime. However, all previous simulations of binary-black-hole inspiral, merger, and ringdown have been limited by an apparently insurmountable barrier: the merging holes' spins could not exceed 0.93, which is still a long way from the maximum possible value in terms of the physical effects of the spin. In this paper, we surpass this limit for the first time, opening the way to explore numerically the behavior of merging, nearly extremal black holes. Specifically, using an improved initial-data method suitable for binary black holes with nearly extremal spins, we simulate the inspiral (through 12.5 orbits), merger and ringdown of two equal-mass black holes with equal spins of magnitude 0.95 antialigned with the orbital angular momentum.