Constraining the Properties of the Thermonuclear Burst Oscillation Source XTE J1814-338 Through Pulse Profile Modelling

TL;DR

This study uses pulse profile modelling to analyze thermonuclear burst oscillations in XTE J1814-338, providing estimates of its fundamental neutron star properties and insights into burst mechanisms.

Contribution

The paper applies relativistic ray-tracing pulse profile modelling to XTE J1814-338, deriving neutron star parameters and highlighting limitations of the uniform hot spot model.

Findings

Estimated distance of 7.2 kpc with uncertainties.

Derived neutron star mass of 1.21 M$_\odot$.

Inferred equatorial radius of 7.0 km.

Abstract

Pulse profile modelling (PPM) is a comprehensive relativistic ray-tracing technique employed to determine the properties of neutron stars. In this study, we apply this technique to the Type I X-ray burster and accretion-powered millisecond pulsar XTE J1814-338, extracting its fundamental properties using PPM of its thermonuclear burst oscillations. Using data from its 2003 outburst, and a single uniform temperature hot spot model, we infer XTE J1814-338 to be located at a distance of $7.2^{+0.3}_{-0.4}$ kpc, with a mass of $1.21^{+0.05}_{-0.05}$ M$_\odot$ and an equatorial radius of $7.0^{+0.4}_{-0.4}$ km. Our results also offer insight into the time evolution of the hot spot but point to some potential shortcomings of the single uniform temperature hot spot model. We explore the implications of this result, including what we can learn about thermonuclear burst oscillation mechanisms and the importance of modelling the accretion contribution to the emission during the burst.