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

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.

Dynamical Scalarization during Neutron Star Mergers in scalar-Gauss-Bonnet Theory

“…Although both NSs are always non-scalarized at the beginning of our simulations, this inaccuracy is "corrected" relatively fast and the tachyonically unstable NS develops scalar field exponentially over a certain timescale (typically 5 ms) after the beginning of simulation. Not starting with consistent scalar field initial data might be unsatisfactory for accurate waveform generation [65] but is sufficient for studying the onset of dynamical scalarization [23,42].…”

Pervasiveness of the breakdown of self-interacting vector field theories

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