Relieving scale disparity in binary black hole simulations

TL;DR

This paper demonstrates the effectiveness of worldtube excision in binary black hole simulations, especially for systems with large mass disparity or early inspiral stages, using scalar charge models to illustrate the technique.

Contribution

It introduces and validates the use of worldtube excision in complex binary black hole simulations, including highly eccentric and hyperbolic orbits, improving computational efficiency.

Findings

Worldtube excision reduces computational costs in binary black hole simulations.

The method is effective for simulating highly eccentric inspirals and scattering scenarios.

Scalar charge models confirm the technique's flexibility and accuracy.

Abstract

Worldtube excision is a method of reducing computational burden in Numerical Relativity simulations of binary black holes in situations where there is a good analytical model of the geometry around (one or both of) the objects. Two such scenarios of relevance in gravitational-wave astronomy are (1) the case of mass-disparate systems, and (2) the early inspiral when the separation is still large. Here we illustrate the utility and flexibility of this technique with simulations of the fully self-consistent radiative evolution in the model problem of a scalar charge orbiting a Schwarzschild black hole under the effect of scalar-field radiation reaction. We explore a range of orbital configurations, including inspirals with large eccentricity (which we follow through to the final plunge and ringdown) and hyperbolic scattering.