INTEGRAL long-term monitoring of the Supergiant Fast X-ray Transient XTE J1739-302

TL;DR

This study analyzes the long-term X-ray behavior of the Supergiant Fast X-ray Transient XTE J1739-302, revealing complex variability patterns that challenge existing models based on clumpy stellar wind accretion.

Contribution

It provides detailed broad-band spectral and temporal analysis of XTE J1739-302, highlighting its complex variability and advancing understanding of SFXT behavior.

Findings

XTE J1739-302 exhibits complex, non-regular variability.

The source shows periods of high, intermediate, and low activity.

Spectral analysis covers 1-200 keV energy range.

Abstract

In the past few years, a new class of High Mass X-Ray Binaries (HMXRB) has been claimed to exist, the Supergiant Fast X-ray Transients (SFXT). These are X-ray binary systems with a compact companion orbiting a supergiant star which show very short and bright outbursts in a series of activity periods overimposed on longer quiescent periods. Only very recently the first attempts to model the behaviour of these sources have been published, some of them within the framework of accretion from clumpy stellar winds.Our goal is to analyze the properties of XTE J1739-302/IGR J17391-3021 within the context of the clumpy structure of the supergiant wind. We have used INTEGRAL and RXTE/PCA observations in order to obtain broad band (1-200 keV) spectra and light curves of XTE J1739-302 and investigate its X-ray spectrum and temporal variability. We have found that XTE J1739-302 follows a much more complex behaviour than expected. Far from presenting a regular variability pattern, XTE J1739-302 shows periods of high, intermediate, and low flaring activity.