Structure and Migration of 2D Vortices

The evolution of 2D vortices is studied in the case of an adiabatic disk. A new vortex model is derived using a gaussian assumption and tested against numerical solutions. This model is compared with previous ones and used as an initial solution for an accurate second order numerical method. Three parameters are necessary to constrain the model: the radial extent of the vortex, its aspect ratio and the local Rossby number. We explore the space of the parameters and find that two different families of vortices can be distinguished: (i) large elongated vortices and (ii) small compact vortices. The shape of the vortices is nearly unchanged even after thousands of rotations. We find that 2D vortices migrate inward at a nearly constant rate that depends on the disk parameters and on the vortex aspect ratio. They appear as quasi-steady structures in Keplerian disks.