Determination of Black Hole Masses in Galactic Black Hole Binaries
Lev Titarchuk
(University of Ferrara, Italy; and NASA Goddard Space Flight Center, USA)
Coauthor(s): Nikolai Shaposhnikov
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I present a study of correlations between X-ray spectral and timing properties observed from a number of Galactic Black Hole (BH) binaries during hard-soft state spectral evolution. We analyze 17 transition episodes from 8 BH sources observed with Rossi X-ray Timing Explorer (RXTE). Our scaling technique for BH mass determination uses a correlation between spectral index and quasi-periodic oscillation (QPO) frequency. In addition, we use a correlation between index and the normalization of the disk ``seed'' component to cross-check the BH mass determination and estimate the distance to the source. In fact, the index-normalization correlation also discloses the index-mass accretion rate saturation effect given that the normalization of disk ``seed'' photon supply is proportional to the disk mass accretion rate. We present arguments that this observationally established index saturation effect is a signature of the bulk motion (converging) flow onto black hole which was early predicted by the dynamical Comptonization theory. We apply our scaling technique to determine BH masses and distances for Cygnus X-1, GX 339-4, 4U 1543-47, XTE J1550-564, XTE J1650-500, H 1743-322 and XTE J1859-226. Good agreement of our results for sources with known values of BH masses and distance provides an independent verification for our scaling technique.