EDP Sciences
Free Access
Volume 393, Number 1, October I 2002
Page(s) 205 - 214
Section Formation, structure and evolution of stars
DOI https://doi.org/10.1051/0004-6361:20020998

A&A 393, 205-214 (2002)
DOI: 10.1051/0004-6361:20020998

On the outbursts of black hole soft X-ray transients

Ü. Ertan1 and M. A. Alpar2

1  Physics Department, Middle East Technical University Ankara 06531, Turkey
2  Sabanci University, Orhanli-Tuzla 81474 Istanbul/ Turkey
    e-mail: alpar@sabanciuniv.edu.tr

(Received 4 March 2002 / Accepted 4 July 2002)

We suggest a new scenario to explain the outburst light curves of black hole soft X-ray transients together with the secondary maximum and the bump seen on their decay phases. Our explanations are based on the disk instability models considering the effect of X-ray irradiation. The scenario is consistent with the observed X-ray delays by a few days with respect to the optical rise for both the main outburst and the later maxima. We test our scenario by numerically solving the disk diffusion equation. The obtained model curve fits well to the observed X-ray outburst photon flux curve of the black hole soft X-ray transient GS/GRS 1124-68, a typical representative of the four BH SXTs with very similar light curves.

Key words: accretion -- accretion disks -- instabilities -- stars: binaries: cose -- X-rays: general

Offprint request: Ü. Ertan, unal@astroa.physics.metu.edu.tr

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