Abstract

During an outburst, accreting black hole binaries (BHB) cycle between quiescence to their Eddington luminosity exhibiting a rich phenomenology that includes thermal and non-thermal X-ray emission, ionized reflection, relativistic jets, quasi-periodic oscillations, and disk winds. The current paradigm dictates that the accretion disk is highly truncated during the jet-dominated hard state, while in the soft state the jet is quenched and the inner-disk is stable at the inner-most circular orbit (ISCO) radius. I will present recent spectroscopy analysis that contradicts this picture. We have found evidence for strong X-ray reflection originated very close to the black hole, suggesting that the disk has reached the ISCO radius at the early phases of the outburst, while the non-thermal coronal emission shows clear signs of evolution in both its electron temperature and optical depth. The implications of these observational findings are discussed in the context of state transitions of several BHBs.