ESA PRESS RELEASE

TRADUCCIÓN AL ESPAÑOL

We have recently discovered a new kind of high mass X-ray binaries which may represent a major subclass. These objects are characterised by the occurrence of very fast X-ray outbursts. Most of the time, they are not detected as X-ray sources or only detected as a waek source. Occasionally, they flare up and, for a very brief period of time, emit strong hard X-ray radiation. Because of the brevity of the outbursts, these X-ray sources had been dubbed fast X-ray transients. Our recent work has shown that, at least a significant fraction of them, are associated with supergiant stars, huge stars that represent the final phase in the life of stars much more massive than the Sun. The connection between supergiant stars and fast transients was rather unexpected. We have called these objects Supergiant Fast X-ray Transients.

Relevant Papers

• I. Negueruela, D. M. Smith,  P. Reig, S. Chaty, & J.M. Torrejón. "Supergiant fast X-ray transients: a new class of high-mas X-ray binaries unveiled by INTEGRAL", 2006, in Proceedings of The X-ray Universe 2005,edited by A. Wilson, ESA SP-604, vol. 1, 165 (it can be downloaded from the ESA webpages or as astro-ph/0511088).


• I. Negueruela, D. M. Smith,  T. E. Harrison , & J.M. Torrejón. "The optical counterpart to the peculiar X-ray source XTE J1739-302" , 2006. Astrophysical Journal, 638, 982  (also at astro-ph/0510675)


• D. M. Smith, W.A. Heindl, C.B. Markwardt, J.H. Swank, I. Negueruela, T.E. Harrison, & L. Huss. "XTE J1739-302 as a supergiant fast X-ray transient", 2006. Astrophysical Journal, 638, 974 (also at astro-ph/0510658)

• I. Negueruela, D. M. Smith,  J.M. Torrejón, & P. Reig. "Supergiant fast X-ray transients: A common behaviour or a class of objects?", Proceedings of the 6th INTEGRAL Workshop "The obscured Universe" , edited by S. Grebenev et al., ESA SP-622, 255 (arXiv:0704.3224).

• I. Negueruela, J.M. Torrejón, P. Reig,M. Ribó, D. M. Smith. "Supergiant Fast X-ray Transients and Other Wind Accretors", to appear in Proceedings of "A population explosion: the nature and evolution of X-ray binaries in diverse environments", edited by R. M. Bandyopadhyay et al.(arXiv:0801.3863).

For an introduction to celestial X-ray sources, check out the X-ray binary page.

Some X-ray sources are not normally detected, or are normally observed as very weak sources, but occasionally display 'outbursts', that is, short periods of activity during which X-ray emission is much stronger. Scientists call these sources transient. Thanks to the capabilities of ESA's gamma-ray observatory INTEGRAL, combined with other space-born X-ray observatories and ground telescopes, a new kind of transients, known as "Supergiant Fast  X-ray Transients" has been discovered.