Supergiant Fast X-ray Transients: interpretation of archival INTEGRAL data

TL;DR

This paper re-analyzes archival INTEGRAL data of Supergiant Fast X-ray Transients, revealing new outbursts and discussing their implications for understanding the wind structures of these high-mass X-ray binaries.

Contribution

It provides the first systematic re-analysis of archival data for multiple SFXTs, discovering previously unnoticed outbursts and offering insights into their wind structures.

Findings

Discovered new outbursts from IGRJ16479-4514 and IGRJ17544-2619.

Revealed variability patterns in SFXTs.

Supported wind structure models explaining outbursts.

Abstract

INTEGRAL monitoring of the Galactic Plane in the last 5 years revealed a new subclass of High Mass X-ray Binaries (HMXBs), the Supergiant Fast X-ray Transients (SFXTs). They display flares lasting from minutes to hours, with peak luminosity of 1E36-1E37 erg/s and a frequent long term flaring activity reaching an X-ray luminosity of 1E33-1E34 erg/s, as recently detected by the Swift satellite. The quiescent level is around 1E32 erg/s. We performed a systematic re-analysis of archival INTEGRAL data of four SFXTs: IGRJ16479-4514, XTEJ1739-302, IGRJ17544-2619, IGRJ18410-0535. This led to the discovery of previously unnoticed outbursts from IGRJ16479-4514 and IGRJ17544-2619. We discuss these results in the framework of the different structure of the supergiant wind proposed to explain the outburst from this new class of sources.