DR. TOMASO BELLONI

Binary systems containing a black hole or a neutron star offer the best possibility to test prediction of General Relativity in the strong field regime. The plasma stripped from the non-degenerate companion star reaches the space time in the immediate vicinity of the compact object and releases strong X-ray emission. The spectral and variability properties of this emission contain the signatures of predicted effects such as the presence of an innermost stable orbit and black hole spin. The speaker will discuss the current observational status with particular emphasis onto sub-second time variability, which constitutes the most direct measurement of the properties of the plasma accreting onto a collapsed star.