Confronting the models of 3:2 QPOs with the evidence of near extreme Kerr black hole

摘要

The black hole mass and spin estimates assuming various specific models ofthe 3:2 high frequency quasi-periodic oscillations (HF QPOs) have been carriedout in Torok et al. (2005, 2011). Here we briefly summarize some currentpoints. Spectral fitting of the spin a=cJ/GM^2 in the microquasar GRS 1915+105reveals 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 havesignificant consequences for the theory of the HF QPOs. The estimate of a>0.9is almost inconsistent with the relativistic precession (RP), tidal disruption(TD), and the warped disc (WD) model. The epicyclic resonance (Ep) anddiscoseismic 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 aserious puzzle because the differences in the individual spins, such as a=0.9compared to a=0.7, represent a generic problem almost for any unified orbital3:2 QPO model.