Supergiant Fast X-ray Transients: A common behaviour or a class of objects?
Abstract
INTEGRAL monitoring of the Galactic Plane is revealing a growing number of recurrent X-ray transients, characterised by short outbursts with very fast rise times (~ tens of minutes) and typical durations of a few hours. A substantial fraction of these sources are associated with OB supergiants and hence define a new class of massive X-ray binaries, which we call Supergiant Fast X-ray Transients. Characterisation of the astrophysical parameters of their counterparts is underway. So far, we have found a number of late O and early B supergiants of different luminosities at a large range of distances. Nothing in their optical properties sets them apart from classical Supergiant X-ray Binaries. On the other hand, there is now rather concluding evidence that persistent supergiant X-ray binaries also show fast outbursts. This suggests a continuum of behaviours between typical persistent supergiant systems and purely transient systems, but offers very little information about the physical causes of the outbursts.
Cite
@article{arxiv.0704.3224,
title = {Supergiant Fast X-ray Transients: A common behaviour or a class of objects?},
author = {Ignacio Negueruela and David M. Smith and Jose Miguel Torrejon and Pablo Reig},
journal= {arXiv preprint arXiv:0704.3224},
year = {2008}
}