Non-radial oscillations of anisotropic neutron stars in the Cowling approximation

TL;DR

This paper investigates how anisotropic pressure affects the non-radial oscillation frequencies of neutron stars using the Cowling approximation, highlighting the potential impact of pressure anisotropy on neutron star models.

Contribution

It introduces the first analysis of non-radial oscillations in anisotropic neutron stars within the Cowling approximation, expanding understanding beyond isotropic models.

Findings

Anisotropy influences oscillation frequencies.

Frequency changes may be indistinguishable from equation of state variations.

First step towards modeling anisotropic neutron star oscillations.

Abstract

One of the most common assumptions in the study of neutron star models and their oscillations is that the pressure is isotopic, however there are arguments that this may not be correct. Thus in the present paper we make a first step towards studying the nonradial oscillations of neutron stars with an anisotropic pressure. We adopt the so-called Cowling approximation where the spacetime metric is kept fixed and the oscillation spectrum for the first few fluid modes is obtained. The effect of the anisotropy on the frequencies is apparent, although with the present results it might be hard to distinguish it from the changes in the frequencies caused by different equations of state.