Hydrodynamical activity in thin accretion disks

An asymptotic treatment of thin accretion disks, introduced by Kluźniak and Kita [Kluźniak, W., Kita, D., 2000. Three-dimensional structure of an alpha accretion disk. Available from: (KK)] for a steady-state disk flow, is extended to a time-dependent problem. Transient growth of axisymmetric disturbances is analytically shown to occur on the global disk scale. The implications of this result on the theory of hydrodynamical thin accretion disks, as well as future prospects, are discussed.