Instabilities of off-centered vortices in a Bose-Einstein condensate
  We study numerically the excitations of off-centered vortices in a Bose-Einstein condensate. The displacement of a single vortex and the separation of a doubly quantized vortex are considered. We find that the core-localized excitations of the precessing vortices continue to feature the property which implies that the vortices are unstable. The core-localized, dipolar, and quadrupolar excitations are found to deform continuously as functions of vortex displacements and intervortex separation. 
Tomoya Isoshima, Jukka Huhtam\"aki and Martti M. Salomaa