Gas Dynamics in a Tidal Interaction: Formation of Rings

Abstract

The authors present two simulations. Nuclear rings form by gravitational torques. In the case of a tidally perturbed galaxy, two waves at different pattern speeds develop. All the gas is gathered towards the center. In contrast, for an isolated galaxy, gas outside corotation is driven outwards. To produce a central starburst or to feed the nucleus, mergers are therefore very efficient. Bars are also, but not as much, since they can gather only gas inside their corotation.