Transient growth and coupling of vortex and wave modes in self-gravitating gaseous discs

Abstract

Flow nonnormality induced linear transient phenomena in thin self-gravitating astrophysical discs are studied in the shearing sheet approximation. The considered system includes two modes of perturbations: vortex and (spiral density) wave. It is shown that self-gravity considerably alters the vortex mode dynamics -- its transient (swing) growth may be several orders of magnitude stronger than in the non-self-gravitating case and 2-3 times larger than the transient growth of the wave mode. Based on this finding, we comment on the role of vortex mode perturbations in a gravitoturbulent state. Also described is the linear coupling of the perturbation modes, caused by the differential character of disc rotation. The coupling is asymmetric -- vortex mode perturbations are able to excite wave mode ones, but not vice versa. This asymmetric coupling lends additional significance to the vortex mode as a participant in spiral density waves and shocks manifestations in astrophysical discs.

10 pages, 8 figures

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• A Parameter Study for Baroclinic Vortex Amplification
• Revisiting linear dynamics of non-axisymmetric perturbations in weakly magnetized accretion discs
• The Observability Of Vortex-Driven Spiral Arms In Protoplanetary Disk: Basic Spiral Properties
• Vortices in self-gravitating gaseous discs
• Spiral structures in gravito-turbulent gaseous disks
• Planetesimal formation in self-gravitating discs -- dust trapping by vortices
• Linear coupling of modes in 2D radially stratified astrophysical discs
• Axisymmetric modes in vertically stratified self-gravitating discs
• Vortex survival in 3D self-gravitating accretion discs
• Boundary Layers of Accretion Disks: Discovery of Vortex-Driven Modes and Other Waves
• On the mechanism of self gravitating Rossby interfacial waves in proto-stellar accretion discs
• Excitation of spiral density waves by convection in accretion discs