Hydro-without-Hydro Framework for Simulations of Black Hole-Neutron Star Binaries

TL;DR

This paper presents a novel computational framework for simulating black hole-neutron star binaries by modeling the neutron star with frozen internal degrees of freedom, avoiding explicit hydrodynamic equations.

Contribution

The framework introduces a new method that simplifies simulations of binary systems by freezing neutron star internal dynamics, enabling efficient pre-merger evolution studies.

Findings

Successfully constructed initial data sets for the binary systems.

Demonstrated the feasibility of the approach through numerical evolutions.

Provided a computational technique that bypasses hydrodynamic equations.

Abstract

We introduce a computational framework which avoids solving explicitly hydrodynamic equations and is suitable to study the pre-merger evolution of black hole-neutron star binary systems. The essence of the method consists of constructing a neutron star model with a black hole companion and freezing the internal degrees of freedom of the neutron star during the course of the evolution of the space-time geometry. We present the main ingredients of the framework, from the formulation of the problem to the appropriate computational techniques to study these binary systems. In addition, we present numerical results of the construction of initial data sets and evolutions that demonstrate the feasibility of this approach.