Accretion Disk Physics:Stability and Oscillations

Stability properties and oscillation modes of accretion disks around compact objects are studied in this paper.Special attentions are paid on the advection-dominated accretion flows, which are shown to be stable against thermal and viscous perturbations.The oscillation modes in a relativistic accretion disk are investigated and some trapped, non-damping modes in the inner disk part can probably be employed to explain the observed quasi-periodic oscillations in X-ray binaries and AGNs