What can we extract from quasi-periodic oscillations?

TL;DR

This paper extends the relativistic precession model to the Hartle-Thorne spacetime, deriving formulas for epicyclic frequencies to interpret kilohertz quasi-periodic oscillations and infer properties of compact objects in X-ray binaries.

Contribution

It provides analytic formulas for epicyclic frequencies in the Hartle-Thorne spacetime and applies them to interpret QPOs, linking observational data to physical parameters of neutron stars.

Findings

QPO data can constrain mass, angular momentum, and quadrupole moment.

Extension of the relativistic precession model to deformed, rotating objects.

Application to Z-source GX 5-1 demonstrates practical utility.

Abstract

In light of the relativistic precession model, we present here detailed analyses, extending the ones performed in the Schwarzschild and Kerr spacetimes. We consider the kilohertz quasi-periodic oscillations in the Hartle-Thorne spacetime, which describes the gravitational field of a rotating and deformed object. We derive the analytic formulas for the epicyclic frequencies in the Hartel-Thorne spacetime and by means of these frequencies we interpret the kilohertz quasi-periodic oscillations of low-mass X-ray binaries of the atoll and Z - sources, on the basis of the relativistic precession model. Particularly we perform analyzes for Z -source: GX 5-1. We show that the quasi-periodic oscillations data can provide information on the parameters, namely, the mass, angular momentum and quadrupole moment of the compact objects in the low-mass X-ray binaries.