Supergiant Fast X-ray Transients with Swift
Abstract
Swift has opened a new way of investigating the phenomenon of Supergiant Fast X-ray Transients (SFXTs), a recently discovered class of High-Mass X-ray Binaries, whose optical counterparts are blue supergiant stars, and whose X-ray outbursts are about 4 orders of magnitude brighter than the quiescent state. Swift's unique contribution has been two-fold.
Thanks to its scheduling flexibility, it has enabled us to regularly monitor a small sample of SFXTs with 2-3 observations (1-2 ks) per week with the X-Ray Telescope (XRT) over their entire visibility period for over 2 years. This has allowed us to study them throughout all phases of their life (outbursts, intermediate level, and quiescence), and to determine the long-term properties and their duty cycle, by means of very sensitive and non-serendipitous observations. Furthermore, the rapid autonomous repointing of Swift has allowed us to catch and study, from optical to hard X-ray, the bright outbursts, and follow them in the X-ray for days, thus determining the shape of their X-ray spectra through simultaneous broadband spectroscopy, and the actual duration of the outburst episodes.- Publication:
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AAS/High Energy Astrophysics Division #11
- Pub Date:
- March 2010
- Bibcode:
- 2010HEAD...11.0103R