IGRJ16479-4514: the first eclipsing supergiant fast X-ray transient?

TL;DR

This study presents the first detailed long-term X-ray observation of IGR J16479-4514, revealing an eclipse and dust scattering effects, advancing understanding of supergiant fast X-ray transients' low activity states.

Contribution

It provides the first long, high-sensitivity X-ray observation of IGR J16479-4514, detecting an eclipse and dust scattering, offering new insights into the behavior of supergiant fast X-ray transients.

Findings

Detected a possible X-ray eclipse by the supergiant companion.

Identified a soft X-ray halo likely due to dust scattering.

Observed low-level emission consistent with gated accretion models.

Abstract

Supergiant fast X-ray transients are a new class of high mass X-ray binaries recently discovered with INTEGRAL. Hours long outbursts from these sources have been observed on numerous occasions at luminosities of ~1E36-1E37 erg/s, whereas their low level activity at ~1E32-1E34 erg/s has not been deeply investigated yet due to the paucity of long pointed observations with high sensitivity X-ray telescopes. Here we report on the first long (~32 ks) pointed XMM-Newton observation of IGR J16479-4514, a member of this new class. This observation was carried out in March 2008, shortly after an outburst from this source, with the main goal of investigating its low level emission and physical mechanisms that drive the source activity. Results from the timing, spectral and spatial analysis of the EPIC-PN XMM-Newton observation show that the X-ray source IGRJ16479-4514 underwent an episode of sudden obscuration, possibly an X-ray eclipse by the supergiant companion. We also found evidence for a soft X-ray extended halo around the source that is most readily interpreted as due to scattering by dust along the line of sight to IGRJ16479-4514. We discuss this result in the context of the gated accretion scenarios that have been proposed to interpret the behaviour of supergiant fast X-ray transient.