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G. Dubus, A. Esin (Caltech), K. Menou (Princeton)
The outbursts of Soft X-ray Transients (SXTs) provide a unique opportunity to study the accretion flows around black holes at different mass transfer rates. In the emission models of Esin et al. (1997), the various X-ray spectral states observed during the decay of SXTs are attributed to the decreasing mass transfer rate and increasing size of a hot advection dominated accretion flow (ADAF). The outburst itself is due to a thermal-viscous instability in the outer thin disk (Dubus et al. 2001).
ADAF models can therefore reproduce the X-ray spectra of SXTs while thin disk models can explain the outburst lightcurves. We report on an attempt to combine the two approaches. The mass accretion rate in the ADAF and the irradiation of the thin disk by X-rays from the ADAF are calculated self-consistently throughout the outburst. We discuss the constraints that can be set onto the evaporation rate (size of the ADAF) and examine whether this model provides a coherent picture of the accretion flows in SXTs or not.
The author(s) of this abstract have provided an email address for comments about the abstract: gd@tapir.caltech.edu