Cosmological k-essence condensation
  We consider a model of dark energy/matter unification based on a k-essence
type of theory similar to tachyon condensate models. Using an extension of the
general relativistic spherical model which incorporates the effects of both
pressure and the acoustic horizon we show that an initially perturbative
k-essence fluid evolves into a mixed system containing cold dark matter like
gravitational condensate in significant quantities.
