June 17, 2009
American Center for Physics
College Park, MD
Speaker: Nikolai Shaposhnikov, NASA Goddard Space Flight Center
Time and Location: Talk starts at 1:00 pm with Q&A to follow. It will be held in one of the first floor conference rooms at the American Center for Physics, One Physics Ellipse, College Park, MD. This is located off River Road, between Kenilworth Ave. and Paint Branch Parkway.
Abstract: I will discuss the latest results on the study of the correlations between spectral and timing properties observed from Galactic Black Hole (BH) sources. I will present the observational picture in terms of transitions between different BH states. Then I plan to describe a physical scenario, which provides a viable explanation for the observed X-ray emission and variability properties and their evolution. Our model is based on the interplay between different types of Comptonization processes in the innermost parts of the accretion flow. Based on our analysis we developed a BH mass measurement method and applied it to a set of Galactic X-ray binaries. I will report on our latest results. We also propose a simple observational signature of BH, which provides a direct test for the presence of a BH horizon, i.e. based on the possible nature of the object as a BH.
Biography: Dr. Nikolai Shaposhnikov received a Bachelor and Master degrees in Applied Physics and Mathematics (Moscow Institute of Physics and Technology, MIPT) in 1994 and 1996 respectively, and obtained a PhD degree in Computational Astrophysics in 2004 from George Mason University. He is now a Research Associate in Goddard Space Flight Center working with the Rossi X-ray Timing Explorer (RXTE) team. His main scientific interests lie in the area of accreting neutron stars and black holes and the physical processes governing accretion onto compact objects. He is contributing to theoretical research concerning the formation of the energy and timing spectra observed from black holes and neutron stars. In parallel, he is actively involved in the analysis of X-ray data from Galactic X-ray binaries.