Pulsation modes for increasingly relativistic polytropes

TL;DR

This paper numerically investigates fluid and gravitational oscillation modes in highly relativistic polytropic stars, revealing long-lived p-modes and confirming previous findings for f and w modes in uniform stars.

Contribution

It provides new numerical results on oscillation modes of relativistic polytropes, highlighting the behavior of p-modes and validating previous uniform density star data.

Findings

f and w modes agree with previous uniform star data

p-modes can become extremely long-lived in relativistic stars

Long-lived p-modes are linked to increased stellar compactness

Abstract

We present the results of a numerical study of the fluid $f$, $p$ and the gravitational $w$ modes for increasingly relativistic nonrotating polytropes. The results for $f$ and $w$-modes are in good agreement with previous data for uniform density stars, which supports an understanding of the nature of the gravitational wave modes based on the uniform density data. We show that the $p$-modes can become extremely long-lived for some relativistic stars. This effect is attributed to the change in the perturbed density distribution as the star becomes more compact.