Analytical Estimate of the Critical Velocity for Vortex Pair Creation in   Trapped Bose Condensates
  We use a modified Thomas-Fermi approximation to estimate analytically the critical velocity for the formation of vortices in harmonically trapped BEC. We compare this analytical estimate to numerical calculations and to recent experiments on trapped alkali condensates. 
M. Crescimanno (1), C. G. Koay (1), R. Peterson (1) and R. Walsworth   (2) ((1) Physics Department, Berea College, (2) Harva...