High-Order Numerical-Relativity Simulations of Binary Neutron Stars

TL;DR

This paper introduces advanced high-order numerical relativity simulations for binary neutron star mergers, significantly improving gravitational waveform accuracy and convergence over traditional methods.

Contribution

It presents the first use of higher-than-second-order schemes in binary neutron star simulations, enhancing waveform quality and convergence robustness.

Findings

Higher-order schemes improve gravitational waveform accuracy.

Reduced de-phasing and faster convergence rates.

Confirmed robustness of high convergence order 3.2.

Abstract

We report simulations of the inspiral and merger of binary neutron stars performed with \texttt{WhiskyTHC}, the first of a new generation of numerical relativity codes employing higher than second-order methods for both the spacetime and the hydrodynamic evolution. We find that the use of higher-order schemes improves substantially the quality of the gravitational waveforms extracted from the simulations when compared to those computed using traditional second-order schemes. The reduced de-phasing and the faster convergence rate allow us to estimate the phase evolution of the gravitational waves emitted, as well as the magnitude of finite-resolution effects, without the need of phase- or time-alignments or rescalings of the waves, as sometimes done in other works. Furthermore, by using an additional unpublished simulation at very high resolution, we confirm the robustness of our high convergence order of $3.2$.