Efficient simulations of high-spin black holes with a new gauge

TL;DR

This paper introduces a new initial data method using spherical Kerr-Schild coordinates that significantly enhances the efficiency of high-spin binary black hole simulations, reducing runtime and improving computational speed.

Contribution

The authors develop a novel initial data approach with spherical Kerr-Schild coordinates, enabling faster and more efficient high-spin black hole simulations.

Findings

Runtime reduced by a factor of 2 for high-spin cases

Delaying gauge transition yields additional speed-up of 1.3

Effective for spins up to 0.99 in binary black hole simulations

Abstract

We present a new choice of initial data for binary black hole simulations that significantly improves the efficiency of high-spin simulations. We use spherical Kerr-Schild coordinates, where the horizon of a rotating black hole is spherical, for each black hole. The superposed spherical Kerr-Schild initial data reduce the runtime by a factor of 2 compared to standard superposed Kerr-Schild for an intermediate resolution spin-0.99 binary-black-hole simulation. We also explore the possibility of delaying the transition from the initial data gauge to the evolution gauge, which produces an additional speed-up of 1.3.