Interaction between a galactic disk and a live dark halo with an   anisotropic velocity distribution
  We have extended previous analytical studies of the interaction of dark halos with galactic disks by introducing for the halo particles anisotropic distribution functions in phase space. For this purpose we have employed the shearing sheet model of a patch of a galactic disk embedded in a homogeneous halo. We find that velocity anisotropy increases considerably the maximum growth factor of perturbations in the disk. 
B. Fuchs and E. Athanassoula