Frequency Correlation of QPOs Based on a Resonantly Excited Disk-Oscillation Model

In previous papers, we have proposed a model in which the high-frequency quasi-periodic oscillations (HF QPOs) observed in black-hole and neutron-star X-ray binaries are inertial-acoustic oscillations that are resonantly excited on a one-armed deformed disk by nonlinear couplings between the oscillations and the disk deformation. In this paper we show that in addition to the inertial-acoustic waves, one-armed corrugation waves are also excited in the deformed disks. They are low-frequency oscillations. We examine the frequencies and their correlations among the inertial-acoustic oscillations and the corrugation waves that are excited, in order to know whether they can describe the observed frequency correlations among kHz QPOs and low-frequency QPOs (LF QPOs) in neutron-star X-ray binaries. The results seem to well describe the observed correlations in Cir X-1, if we adopt $M=$ 1.5–2.0$M_\odot$ and $a_* \sim 0.8$, where $M$ is the mass of the central star and $a_*$ is a dimensionless spin parameter of the metric. Finally, assumptions involved in this disk-oscillation model are briefly summarized and discussed.

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