Low-Frequency Oscillations of Relativistic Accretion Disks

A recently developed formalism for computing the pulsations of rapidly rotating fluid configurations in general relativity is reviewed. A summary is given of results for modes of a relativistic accretion disk around a Kerr black hole. The disk’s self-gravity is neglected, and attention is focused on the existence of modes with very low frequencies and their possible connection with the quasi-periodic-oscillation phenomena exhibited by certain black-hole candidates. The calculations reviewed indicate that in many cases thin relativistic disks exhibit warped precession modes with very low frequencies in the observed range. Effects associated with the dragging of inertial frames play a crucial role in determining the values of the frequencies. These effects allow an explanation, in terms of a common mechanism, for the full range of frequencies of observed quasi-periodic oscillations.