Podrobný výpis o publikaci

The black hole mass and spin estimates assuming various specific models of the 3 : 2 high frequency quasi-periodic oscillations (HF QPOs) have been carried out in Török et al. (2005, 2011). Here we briefly summarize some current points. Spectral fittingof the spin a = cJ/GM 2 in the microquasar GRS 1915 + 105 reveals that this system can contain a near extreme rotating black hole (e.g., McClintock et al., 2011). Confirming the high value of the spin would have significant consequences for the theory ofthe HF QPOs. The estimate of a > 0.9 is almost inconsistent with the relativistic precession (RP), tidal disruption (TD), and the warped disc (WD) model. The epicyclic resonance (Ep) and discoseismic models assuming the c- and g- modes are instead favoured. However, consideration of all three microquasars that display the 3 : 2 HF QPOs leads to a serious puzzle because the differences in the individual spins, such as a = 0.9 compared to a = 0.7, represent a generic problem almost for an