Nonlinear studies of binary black hole mergers in Einstein-scalar-Gauss-Bonnet gravity

TL;DR

This paper investigates the nonlinear dynamics of binary black hole mergers in Einstein-scalar-Gauss-Bonnet gravity, analyzing scalar and gravitational wave emissions through numerical simulations and comparing them with post-Newtonian predictions.

Contribution

It provides the first detailed numerical study of binary black hole mergers in Einstein-scalar-Gauss-Bonnet gravity, highlighting the limitations of post-Newtonian models near merger.

Findings

Post-Newtonian theory accurately models scalar waveform amplitude during inspiral.

Post-Newtonian theory is insufficient for modeling gravitational wave dephasing near merger.

Nonlinear scalar field enhancement occurs at merger with minimal impact on gravitational wave peak emission.

Abstract

We study the nonlinear dynamics of binary black hole systems with scalar charge by numerically evolving the full equations of motion for shift-symmetric Einstein scalar Gauss-Bonnet gravity. We consider quasi-circular binaries with different mass-ratios, varying the Gauss-Bonnet coupling and quantifying its impact on the emitted scalar and gravitational waves. We compare our numerical results to post-Newtonian calculations of the radiation emitted during the inspiral. We demonstrate the accuracy of the leading-order terms in post-Newtonian theory in modeling the amplitude of the scalar waveform, but find that, at least for the last few orbits before merger, the currently available post-Newtonian theory is not sufficient to model the dephasing of the gravitational wave signal in this theory. We further find that there is non-negligible nonlinear enhancement in the scalar field at merger, but that the effect on the peak gravitational wave emission is small.