Axial quasi-normal modes of Einstein-Gauss-Bonnet-dilaton neutron stars

TL;DR

This study analyzes axial quasi-normal modes of neutron stars within Einstein-Gauss-Bonnet-dilaton gravity, revealing increased mode frequencies and preserved universal relations, which can help constrain the theory's parameters.

Contribution

It extends the analysis of neutron star oscillations to Einstein-Gauss-Bonnet-dilaton gravity and demonstrates the applicability of universal relations for constraining the coupling.

Findings

Mode frequencies increase with Gauss-Bonnet-dilaton presence

Universal relations remain valid in the modified gravity context

Proposed method to constrain Gauss-Bonnet coupling using phenomenological relations

Abstract

We investigate axial quasi-normal modes of realistic neutron stars in Einstein-Gauss-Bonnet-dilaton gravity. We consider 8 realistic equations of state containing nuclear, hyperonic, and hybrid matter. We focus on the fundamental curvature mode and compare the results with those of pure Einstein theory. We observe that the frequency of the modes is increased by the presence of the Gauss-Bonnet-dilaton, while the impact on the damping time is typically smaller. Interestingly, we obtain that universal relations valid in pure Einstein theory still hold for Einstein-Gauss-Bonnet-dilaton gravity, and we propose a method to use these phenomenological relations to constrain the value of the Gauss-Bonnet coupling.