Gravitational waves from pulsations of neutron stars described by realistic Equations of State

TL;DR

This paper investigates gravitational wave signals from pulsating neutron stars with realistic equations of state, analyzing mode frequencies and waveform accuracy through long-term numerical simulations.

Contribution

It introduces a stable numerical method for evolving neutron star perturbations with realistic EOS and accurately extracting gravitational wave modes.

Findings

Accurate mode frequencies comparable to frequency domain methods

Stable long-term evolution of neutron star perturbations

Waveform analysis useful for nonlinear oscillation simulations

Abstract

In this work we discuss the time-evolution of nonspherical perturbations of a nonrotating neutron star described by a realistic Equation of State (EOS). We analyze 10 different EOS for a large sample of neutron star models. Various kind of generic initial data are evolved and the corresponding gravitational wave signals are computed. We focus on the dynamical excitation of fluid and spacetime modes and extract the corresponding frequencies. We employ a constrained numerical algorithm based on standard finite differencing schemes which permits stable and long term evolutions. Our code provides accurate waveforms and allows to capture, via Fourier analysis of the energy spectra, the frequencies of the fluid modes with an accuracy comparable to that of frequency domain calculations. The results we present here are useful for provindig comparisons with simulations of nonlinear oscillations of (rotating) neutron star models as well as testbeds for 3D nonlinear codes.