Understanding Black Holes: Spin, Disk and State Transition

Observations from XMM-Newton and other X-ray telescopes have shown how relativistic disk lines, together with the thermal continuum, can be used to precisely constrain the nature of the compact object in XRB systems, as well as that of the accretion flow. The importance of XMM-Newton in the study of black hole binaries cannot be overemphasised; with a single 40ksec (total) XMM-Newton observation of XTE J1752-223 (AO-9), we found that --- at least for this specific source --- state transition is not a manifestation of a change in the inner extent of the accretion disk; we confirmed the black hole nature of the central source; and constrained its dimensionless spin parameter. Here, we propose to build on this success through a single 40ksec (total) ToO observation of a black hole transient in outburst.