Oscillations of rapidly rotating relativistic stars

TL;DR

This study investigates the oscillation spectra of rapidly rotating relativistic stars using the Cowling approximation, revealing how fast rotation influences oscillation modes and potential gravitational wave signals.

Contribution

First analysis of non-axisymmetric oscillations in rapidly rotating relativistic stars using Fourier methods, providing new insights into rotation effects and stability limits.

Findings

Rotation affects oscillation spectra significantly.

Identified limits for secular bar mode instability.

Provided approximate formulas for spectrum dependence on rotation.

Abstract

Non-axisymmetric oscillations of rapidly rotating relativistic stars are studied using the Cowling approximation. The oscillation spectra have been estimated by Fourier transforming the evolution equations describing the perturbations. This is the first study of its kind and provides information on the effect of fast rotation on the oscillation spectra while it offers the possibility in studying the complete problem by including spacetime perturbations. Our study includes both axisymmetric and non-axisymmetric perturbations and provides limits for the onset of the secular bar mode rotational instability. We also present approximate formulae for the dependence of the oscillation spectrum from rotation. The results suggest that it is possible to extract the relativistic star's parameters from the observed gravitational wave spectrum.