Hyperboloidal neutron star and black hole initial data in spherical symmetry

TL;DR

This paper presents the first construction of hyperboloidal initial data for neutron stars and black holes in spherical symmetry, enabling future evolutions of Einstein and hydrodynamic equations on such slices.

Contribution

It introduces a novel method for constructing hyperboloidal initial data including neutron stars and black holes in spherical symmetry, filling a gap in numerical relativity.

Findings

Successfully constructed hyperboloidal initial data for neutron stars.

Extended the data to include neutron star-black hole systems.

Data are suitable for evolution of Einstein and hydrodynamic equations.

Abstract

The focus of this work is on the construction of initial data including a neutron star on a hyperboloidal slice. As simplest scenario for this first step, spherical symmetry is considered together with a polytropic-like equation of state for the neutron star. Constraint-satisfying hyperboloidal initial data are obtained for a single neutron star and for a combination of neutron star with a black hole in its center. To the author's best knowledge this is the first time that full hyperboloidal slices of a neutron star spacetime are constructed. The obtained initial data are suitable for evolutions of the Einstein and relativistic hydrodynamic equations on hyperboloidal slices.