Kelvin-Helmholtz Instability of Counter-Rotating Discs

Abstract

Observations of galaxies and models of accreting systems point to the occurrence of counter-rotating discs where the inner part of the disc ($r<r_0$) is co-rotating and the outer part is counter-rotating. This work analyzes the linear stability of radially separated co- and counter-rotating thin discs. The strong instability found is the supersonic Kelvin-Helmholtz instability. The growth rates are of the order of or larger than the angular rotation rate at the interface. The instability is absent if there is no vertical dependence of the perturbation. That is, the instability is essentially three-dimensional. The nonlinear evolution of the instability is predicted to lead to a mixing of the two components, strong heating of the mixed gas, and vertical expansion of the gas, and annihilation of the angular momenta of the two components. As a result the heated gas will free-fall towards the disc's center over the surface of the inner disc.

References in corpus (3)

• Fuelling Active Galactic Nuclei
• Stability of the Magnetopause of Disk-Accreting Rotating Stars
• Counter-Rotation in Disk Galaxies

Cited by in corpus (4)

• Compaction and Quenching of High-z Galaxies in Cosmological Simulations: Blue and Red Nuggets
• Dynamical evidence of the sub-parsec counter-rotating disc for a close binary of supermassive black holes in the nucleus of NGC 1068
• Disk heating and bending instability in galaxies with counterrotation
• From the Circumnuclear Disk in the Galactic Center to thick, obscuring tori of AGNs -- Modelling the molecular emission of a parsec-scale torus as found in NGC1068