Post-Newtonian Gravitational and Scalar Waves in Scalar-Gauss-Bonnet Gravity

TL;DR

This paper models gravitational and scalar wave emissions from black hole binaries in scalar-Gauss-Bonnet gravity, including nonlinear effects, to aid in testing deviations from General Relativity with gravitational wave observations.

Contribution

It derives the first post-Newtonian order waveforms beyond the quadrupole approximation in scalar-Gauss-Bonnet gravity, incorporating nonlinear curvature contributions.

Findings

Nonlinear curvature terms significantly affect waveforms.

Black hole scalar charges influence detectability of deviations.

Comparison with numerical relativity validates the scalar waveform models.

Abstract

Gravitational waves emitted by black hole binary inspiral and mergers enable unprecedented strong-field tests of gravity, requiring accurate theoretical modelling of the expected signals in extensions of General Relativity. In this paper we model the gravitational wave emission of inspiraling binaries in scalar Gauss-Bonnet gravity theories. Going beyond the weak-coupling approximation, we derive the gravitational waveform to first post-Newtonian order beyond the quadrupole approximation and calculate new contributions from nonlinear curvature terms. We quantify the effect of these terms and provide ready-to-implement gravitational wave and scalar waveforms as well as the Fourier domain phase for quasi-circular binaries. We also perform a parameter space study, which indicates that the values of black hole scalar charges play a crucial role in the detectability of deviation from General Relativity. We also compare the scalar waveforms to numerical relativity simulations to assess the impact of the relativistic corrections to the scalar radiation. Our results provide important foundations for future precision tests of gravity.