Decade-long X-ray observations of HESS J0632+057

TL;DR

This paper presents a comprehensive analysis of a decade of X-ray data from HESS J0632+057, refining its orbital parameters and exploring emission mechanisms, with implications for understanding gamma-ray binary systems.

Contribution

It provides the most accurate orbital period measurement and proposes an inclined disk model to explain observed X-ray variability and emission mechanisms.

Findings

Refined orbital period to 316.8 days with high precision.

Detected spectral slope and hydrogen column density variations along the orbit.

Suggested emission from a broken power-law electron population and proposed observational tests.

Abstract

We present results of a decade of X-ray observations of the gamma-ray loud binary HESS J0632+057, and interpret the available broadband data in view of the system geometry and emission mechanisms. We have performed an analysis of all X-ray data available to date from Swift, XMM-Newton, Chandra, NuSTAR and Suzaku. We refine the orbital period of the system to be $316.8^{+2.6}_{-1.4}$~d (95% c.l.), consistent with previous studies but measured with significantly better accuracy. We report on a hydrogen column density and spectral slope variation along the orbit. We argue that the observed variability can be explained within an "inclined disk" model in which the orbit of the compact object is inclined to the disk of the Be star. We show that the observed X-ray to TeV emission can originate from a broken cut-off power-law population of electrons and describe a way in which future X-ray/TeV observations can distinguish between the proposed model and the alternative flip-flop emission scenario of this system.