Conformally Flat Smoothed Particle Hydrodynamics: Application to Neutron Star Mergers

TL;DR

This paper introduces a new 3D smoothed particle hydrodynamics code for simulating neutron star mergers within a conformally flat approximation, enabling detailed analysis of gravitational waves and mass ejection.

Contribution

The paper presents a novel 3D SPH code that solves relativistic equations in the conformally flat approximation and applies it to neutron star mergers, including gravitational wave and mass ejection analysis.

Findings

Successful simulation of neutron star coalescence

Calculation of gravitational wave signals and spectra

Assessment of mass ejection during mergers

Abstract

We present a new 3D SPH code which solves the general relativistic field + hydrodynamics equations in the conformally flat approximation. Several test cases are considered to test different aspects of the code. We finally apply then the code to the coalescence of a neutron star binary system. The neutron stars are modeled by a polytropic equation of state (EoS) with adiabatic indices $\Gamma=2.0$, $\Gamma=2.6$ and $\Gamma=3.0$. We calculate the gravitational wave signals, luminosities and frequency spectra by employing the quadrupole approximation for emission and back reaction in the slow motion limit. In addition, we consider the amount of ejected mass.