Faculty of Engineering and Natural Sciences
Populations of Accreting Black Holes and Neutron Stars in Galaxies
Dr. Marat Gilfanov
Max-Planck-Institute for Astrophysics, Garching
I will summarize current status of our understanding of populations of accreting X-ray sources in galaxies. The luminosity distributions of X-ray binaries in star-forming and elliptical galaxies observed by Chandra and XMM-Newton are well described by respective "universal" luminosity functions. There is a qualitative difference between LFs of high- and low-mass X-ray binaries, reflecting the difference in the accretion regimes in these two types of X-ray binaries. The numbers of high-mass X-ray binaries observed in star-forming galaxies indicate the rather high probablity for a massive star to become an accretion powered X-ray source once upon its lifetime. This explains surprisingly high contribution of accreting neutron stars and stellar mass black holes to the Cosmic X-ray background, ~7-10%. Finally, I will present the evidence that low-mass X-ray binaries may be formed in significant numbers near galactic centers via tidal captures of low mass stars by stellar mass black holes.
July 9, 2008 Wednesday, 13:40, FENS G032