Stellar oscillations in Eddington-inspired Born-Infeld gravity

TL;DR

This study investigates how stellar oscillation frequencies in relativistic stars are affected by Eddington-inspired Born-Infeld gravity, revealing potential observational signatures to distinguish it from general relativity.

Contribution

The paper derives perturbation equations for stellar oscillations in EiBI gravity and shows how frequencies vary with the coupling parameter, providing a method to test EiBI against GR.

Findings

Oscillation frequencies depend strongly on the EiBI coupling parameter 

Negative  increases frequencies; positive  decreases them compared to GR

Fundamental frequency observations can distinguish EiBI from GR for certain parameter ranges

Abstract

We consider the stellar oscillations of relativistic stars in the Eddington-inspired Born-Infeld gravity (EiBI). In order to examine the specific frequencies, we derive the perturbation equations governing the stellar oscillations in EiBI by linearizing the field equations, and numerically determine the oscillation frequencies as changing the coupling parameter in EiBI, $\kappa$, and stellar models. As a result, we find that the frequencies depend strongly on the value of $\kappa$, where the frequencies in EiBI with negative $\kappa$ become higher and those with positive $\kappa$ become lower than the expectations in general relativity. We also find that, via the observation of the fundamental frequency, one could distinguish EiBI with $8\pi\epsilon_0|\kappa|\gtrsim 0.03$ from general relativity, independently of the equation of state (EOS) for neutron star matter, where $\epsilon_0$ denotes the nuclear saturation density and $\epsilon_0\kappa$ become dimensionless parameter. With the further constraints on EOS, one might distinguish EiBI even with $8\pi\epsilon_0|\kappa|\lesssim 0.03$ from general relativity.