Gravitational instability of gasdust circumnuclear disks in nearby galaxies

Abstract

Using the two-dimensional multi-component hydrodynamical simulations, we study the effect of dust on the development of instability in the gas-dust mini-disks observed in the central regions of galaxies. The dust is coupled with the gas gravitationally and by means of a friction force depending on the velocity difference between the two components. The presence of dust leads to the instability of a mini-disk and the development of a spiral structure observed in the gas-dust mini-disks. The spiral structure is multi-armed, which is caused by a dominance of the high order Fourier harmonics in the unstable modes. The instability of gas-dust circumnuclear disks is an important mechanism for explaining the activity of galactic nuclei associated with the accretion of matter onto a central black hole. We find that the admixture of dust with a dust-to-gas ratio of 10–20% significantly destabilizes the gas-dust disk.