Publication date: Dec 2004
Abstract:
In all four microquasars which show twin peak kHz QPOs, the ratio of the two frequencies is 3:2. This rather strongly supports the suggestion by Abramowicz, M. A. and Kluzniak [W. Abramowicz, M. A. and Kluzniak, W., (2001). A precise determination of black hole spin in GRO J1655-40. Astronomy and Astrophysics, 374:L19] that twin peak kHz QPOs are due to a resonance between some modes of accretion disk oscillations. Detailed studies of this suggestion revealed that several such non-linear resonances are present in nearly Keplerian disks in strong gravity. Here, we fit to observations predictions of the resonance hypothesis for two particular types of non-linear resonances between vertical and radial epicyclic frequencies. For three microquasars with known masses, the fits give an accurate estimate of the spin.
Authors:
Abramowicz, Marek A.; Kluzniak, Włodek; Stuchlík, Zdeněk; Török, Gabriel;