A new numerical method to construct binary neutron star initial data

TL;DR

This paper introduces a novel spectral numerical method for generating initial data of binary neutron star systems, improving boundary condition handling and computational efficiency within the conformal thin sandwich framework.

Contribution

The paper presents a new spectral method using multiple domains with boundary-aligned star surfaces, enhancing the generation of binary neutron star initial data.

Findings

Successfully implemented corotating configurations with various mass ratios

Efficiently solves elliptic equations using pseudospectral methods

Facilitates boundary condition imposition at star surfaces and spatial infinity

Abstract

We present a new numerical method for the generation of binary neutron star initial data using a method along the lines of the the Wilson-Mathews or the closely related conformal thin sandwich approach. Our method uses six different computational domains, which include spatial infinity. Each domain has its own coordinates which are chosen such that the star surfaces always coincide with domain boundaries. These properties facilitate the imposition of boundary conditions. Since all our fields are smooth inside each domain, we are able to use an efficient pseudospectral method to solve the elliptic equations associated with the conformal thin sandwich approach. Currently we have implemented corotating configurations with arbitrary mass ratios, but an extension to arbitrary spins is possible. The main purpose of this paper is to introduce our new method and to test our code for several different configurations.