HEAD 2000, November 2000
Session 34. Gamma-Ray Bursts
Display, Thursday, November 9, 2000, 8:00am-6:00pm, Bora Bora Ballroom

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[34.09] Soft Gamma-Ray Repeaters as Neutron Star-White Dwarf Relativistic Binaries

H. J. Mosquera Cuesta (Abdus Salam International Centre for Theoretical Physics)

Compelling evidence is accumulating against the picture suggesting that soft gamma-ray repeaters (SGRs) are magnetars. A scenario is introduced, in which gravitational radiation (GR) reaction effects drive the SGRs dynamics of an ultrashort orbital period X-ray binary embracing a mid-mass donor white dwarf(WD) to a rapidly rotating low magnetized high-mass neutron star (NS) surrounded by a thick dense massive accretion torus. Driven by GR, sparsely, the binary separation reduces and the WD overflows its Roche lobe, drives unstable the accretion disk around, and starts to pulsate radially due to the powerful irradiation from the fireball following the disk matter slumping onto the NS. This model allows to explain most of SGRs observational features, particularly the intriguing subpulses recently discovered by BeppoSAX, which are suggested here to be overtones of the WD radial fundamental mode. New \gamma-rays and X-rays satellites like CHANDRA, and the forthcoming generation of GR detectors such as LIGO, VIRGO, GEO-600 and TIGAs (burster phase) and LISA space observatory (orbital dynamics) may do their best so as to study SGRs evolution farther out of the weak-field gravity regime.

The author(s) of this abstract have provided an email address for comments about the abstract: herman@ictp.trieste.it

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