Perturbative Analysis of Universality and Individuality in Gravitational Waves from Neutron Stars

TL;DR

This paper investigates the universal features of gravitational wave spectra from non-rotating neutron stars, using a simplified model and perturbation theory to explain and predict these phenomena.

Contribution

It introduces the scaled coordinate logarithmic perturbation theory (SCLPT) and demonstrates its effectiveness in modeling universality and individual differences in neutron star gravitational waves.

Findings

CBA captures the essence of the Tolman VII model.

SCLPT explains and predicts universal spectral behavior.

Individual neutron star modes can be derived from CBA with SCLPT.

Abstract

The universality observed in gravitational wave spectra of non-rotating neutron stars is analyzed here. We show that the universality in the axial oscillation mode can be reproduced with a simple stellar model, namely the centrifugal barrier approximation (CBA), which captures the essence of the Tolman VII model of compact stars. Through the establishment of scaled co-ordinate logarithmic perturbation theory (SCLPT), we are able to explain and quantitatively predict such universal behavior. In addition, quasi-normal modes of individual neutron stars characterized by different equations of state can be obtained from those of CBA with SCLPT.