Quasiperiodic oscillations in a strong gravitational field around neutron stars testing braneworld models

TL;DR

This paper explores how a brany tidal charge influences quasiperiodic oscillations around neutron stars, providing a modified relativistic precession model that fits observational data and constrains brane-world parameters.

Contribution

It introduces a modified relativistic precession model incorporating tidal charge effects, linking neutron star QPOs to brane-world gravity theories.

Findings

Tidal charge affects QPO frequency profiles.

Model fits observational data with specific tidal charge values.

Constraints on brane tension from strong-field regimes.

Abstract

The strong gravitational field of neutron stars in the brany universe could be described by spherically symmetric solutions with a metric in the exterior to the brany stars being of the Reissner-Nordstrom type containing a brany tidal charge representing the tidal effect of the bulk spacetime onto the star structure. We investigate the role of the tidal charge in orbital models of high-frequency quasiperiodic oscillations (QPOs) observed in neutron star binary systems. We focus on the relativistic precession model. We give the radial profiles of frequencies of the Keplerian (vertical) and radial epicyclic oscillations. We show how the standard relativistic precession model modified by the tidal charge fits the observational data, giving estimates of the allowed values of the tidal charge and the brane tension based on the processes going in the vicinity of neutron stars. We compare the strong field regime restrictions with those given in the weak-field limit of solar system experiments.