Accurate and realistic initial data for black hole-neutron star binaries

TL;DR

This paper presents a highly accurate method for computing initial data of black hole-neutron star binaries using spectral methods, improving precision over previous models and including realistic neutron star compactness.

Contribution

The paper introduces a new spectral method for initial data computation that achieves higher accuracy and incorporates realistic neutron star compactness.

Findings

Enhanced accuracy of initial data compared to previous codes

Sequences with realistic neutron star compactness are generated for the first time

Validation against previous models in high mass ratio and low compactness regimes

Abstract

This paper is devoted to the computation of compact binaries composed of one black hole and one neutron star. The objects are assumed to be on exact circular orbits. Standard 3+1 decomposition of Einstein equations is performed and the conformal flatness approximation is used. The obtained system of elliptic equations is solved by means of multi-domain spectral methods. Results are compared with previous work both in the high mass ratio limit and for one neutron star with very low compactness parameter. The accuracy of the present code is shown to be greater than with previous codes. Moreover, for the first time, some sequences containing one neutron star of realistic compactness are presented and discussed.