Титарчук Лев Григорьевич   (NRL)

Determination of Black Hole Masses in Galactic X-ray Binaries using Scaling of Spectral Index and Quasi-Periodic Oscillation Frequency Correlation // Николай Шапошников

We present analysis of the evolution of spectral and timing properties of a number of Galactic black hole (BH) sources during transition between spectral states in order to study the implications of scaling between the centroid of the low frequency quasi-periodic oscillations (QPO) and photon index of Comptonized component in the energy spectrum. We show the analysis of low-hard and intermediate states of sources XTE J1550-564, H 1743-322, GX 339-4, XTE J1859-226, XTE J1650-500 and GRS 1915+105. We find a robust correlation between QPO frequency and photon index for all these six sources. We investigate the implication of the QPO frequency-index scaling for determination BH masses in these sources. We discover that the the QPO-index correlation curves observed in XTE J1550-564, H 1743-322 and GX 339-4 are strikingly close each other, which indicate that these sources should have very close BH masses. This implies that BH masses in H 1743-322 and GX 339-4 are about BH mass in XTE J1550-564, i.e solar masses that early determined using optical and X-ray spectroscopic methods. Directly applying the scaling technique we also obtain that a ratio of the BH masses in XTE J1859-226 and in XTE J1550-564 is , and the corresponding ratio for XTE J1650-500 and XTE J1550-564 is . These values of scaling factors r implies that BH masses are ; solar masses in XTE J1859-226 and XTE J1650-500 respectively. We argue that the correlation pattern exhibited by 4U 1630-47 and GRS 1915+105 are self-similar and it is different from that in XTE J1550-564 and related sources. Using scaling between 4U 1630-47 and GRS 1915+105 for which the scaling factor and early determined BH mass being in GRS 1915+105 we find that BH mass is solar masses in 4U 1630-47. We also demonstrate that the saturation index vs QPO frequency detected in a number of sources is an observational signature of the converging flow into black holes.