Swift monitoring of supergiant fast X-ray transients: The out-of-outburst behaviour and the flares from IGR J17544-2916 and XTE J1739-302

L. Sidoli, P. Romano, G. Cusumano, V. Mangano, S. Vercellone, A. Paizis, A. Pellizzoni, Jamie A. Kennea, David Nelson Burrows, H. A. Krimm, N. Gehrels, C. Guidorzi, P. A. Evans

Research output: Contribution to journalConference article

Abstract

Supergiant Fast X-ray Transients (SFXTs) are a sub-class of High Mass X-ray Binaries (HMXBs) associated with OB supergiant companions and displaying transient X-ray activity. This behaviour is quite surprising since HMXBs hosting supergiants were known to be persistent sources, until the INTEGRAL discoveries obtained by means of the monitoring of the Galactic plane. We have been performing a monitoring campaign with Swift of four SFXTs with the main aim of characterizing both the long-term behaviour of these transients and the properties during bright outbursts. Here we discuss the properties of the X-ray emission observed outside the outbursts as well as the flares observed from two SFXTs: IGR J17544-2916 and XTE J1739-302. Contrarily to what previously thought, Swift allowed us to discover that SFXTs spend most of the time in accretion at a low level, even outside the bright outbursts, with an accretion luminosity of 1033-1034 erg s-1, and that the quiescent level ∼1032 erg s-1, is a much rarer state.

Original languageEnglish (US)
JournalProceedings of Science
StatePublished - Dec 1 2008
Event7th INTEGRAL Workshop - An INTEGRAL View of Compact Objects, INTEGRAL 2008 - Copenhagen, Denmark
Duration: Sep 8 2008Sep 11 2008

All Science Journal Classification (ASJC) codes

  • General

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    Sidoli, L., Romano, P., Cusumano, G., Mangano, V., Vercellone, S., Paizis, A., Pellizzoni, A., Kennea, J. A., Burrows, D. N., Krimm, H. A., Gehrels, N., Guidorzi, C., & Evans, P. A. (2008). Swift monitoring of supergiant fast X-ray transients: The out-of-outburst behaviour and the flares from IGR J17544-2916 and XTE J1739-302. Proceedings of Science.