Dark-Matter Admixed Neutron Stars
  We study the hydrostatic equilibrium configuration of an admixture of
degenerate dark matter and normal nuclear matter by using a general
relativistic two-fluid formalism. We consider non- self-annihilating dark
matter particles of mass ~ 1 GeV. The mass-radius relations and moments of
inertia of these dark-matter admixed neutron stars are investigated and the
stability of these stars is demonstrated by performing a radial perturbation
analysis. We find a new class of compact stars which consists of a small normal
matter core with radius of a few km embedded in a ten-kilometer- sized dark
matter halo. These stellar objects may be observed as extraordinarily small
neutron stars that are incompatible with realistic nuclear matter models.
