Speaker
Description
Tomaso and I were the first post-doc and PhD student, respectively, of Michiel van der Klis when he became professor at the API in Amsterdam. Afterwards, in time at various meetings we interacted and even combined our research interests, especially related to (absorption) dips in the light curves of black-hole X-ray binaries.
In a paper in 1996, Tomaso with colleagues reported on an intermediate state seen in Cyg X-1. They concluded that "Perhaps also the state transitions of Cyg X-1 observed in the 1970s were not to a high state but to this intermediate state" and "In earlier observations Cyg X-1 may have been encountered in this intermediate state as well, and it is possible that the earlier reports of state transitions also involved such an intermediate state." From a new study of the fast-time variability in observations from the 1970s, I confirm that at various times Cyg X-1 indeed transited from the soft to hard state and vice versa.