XMM-Newton observations of two black hole X-ray transients in quiescence
Résumé
The X-ray spectrum of GRO J1655-40 is very hard as it can be fitted with a power law model of photon index ~ 1.3+/- 0.4. Similarly hard spectra have been observed from other systems; these rule out coronal emission from the secondary or disk flares as the origin of the observed X-rays. On the other hand, our observations are consistent with the predictions of the disc instability model in the case that the accretion flow forms an advection dominated accretion flow (ADAF) at distances less than a fraction ( ~ 0.1-0.3) of the circularization radius. This distance corresponds to the greatest extent of the ADAF that is thought to be possible.
Origine | Fichiers éditeurs autorisés sur une archive ouverte |
---|