Spin of Stellar-Mass Black Holes Estimated by a Model of Quasi-Periodic Oscillations

astro-ph/0608578 [abs, ps, pdf, other] :

Title: Spin of Stellar-Mass Black Holes Estimated by a Model of Quasi-Periodic Oscillations
Authors: Shoji Kato, Jun Fukue
Comments: 12 pages, 6 figures, PASJ 58 (in press)

We have proposed in previous papers that the high-frequency pair QPOs observed in black-hole binaries with frequency ratio 3:2 are inertial-acoustic oscillations (nearly horizontal oscillations with no node in the vertical direction) or g-mode oscillations, which are resonantly excited on warped relativistic disks. The resonance occurs through horizontal motions. In this model the dimensionless spin parameter $a_*$ of the central sources can be estimated when their masses are known from other observations. This estimate is done for three sources (GRO J1665-40, XTE J1550-564, GRS 1915+105). For all of them we have $a_*\leq 0.45$.