High-frequency quasi-periodic oscillations and oscillations of accretion disks

Accreting black holes and neutron stars show remarkable variability in their X-ray light curves. In this talk, we will concentrate on the high-frequency variability and its possible theoretical explanations. Most of the attention will be devoted to models based on the orbital motion and oscillations of geometrically thin accretion disks. After brief presentation of disk linear modes, we will discuss their nonlinear interactions and resonances.