A new explanation for the SFXTs outbursts

TL;DR

This paper proposes a new explanation for the short outbursts in Supergiant Fast X-ray Transients, suggesting a second equatorial wind component from the supergiant companion as the cause, based on recent observations.

Contribution

It introduces a novel model linking SFXT outbursts to a second wind component, explaining both periodic and non-periodic outbursts in these systems.

Findings

Observations of IGRJ11215-5952 support the new wind-based outburst model.

The model accounts for short outburst durations in all SFXTs.

It also encompasses persistent supergiant HMXBs within the same framework.

Abstract

The physical mechanism responsible for the short outbursts in a recently recognized class of High Mass X-ray Binaries, the Supergiant Fast X-ray Transients (SFXTs), is still unknown. Recent observations performed with Swift/XRT, XMM-Newton and INTEGRAL of the 2007 outburst from IGRJ11215-5952, the only SFXT known to exhibit periodic outbursts, suggest a new explanation for the outburst mechanism in this class of transients, linked to the possible presence of a second wind component in the supergiant companion, in the form of an equatorial wind. The applicability of the model to the short outburst durations of all other SFXTs, where a clear periodicity in the outbursts has not been found yet, is discussed. The scenario we are proposing also includes the persistently accreting supergiant High Mass X-ray Binaries.