Beyond Spherical Top Hat Collapse
  We study the evolution of inhomogeneous spherical perturbations in the
universe in a way that generalizes the spherical top hat collapse in a
straightforward manner. For that purpose we derive a dynamical equation for the
evolution of the density contrast in the context of a Lemaitre-Tolman-Bondi
metric and construct solutions with and without a cosmological constant for the
evolution of a spherical perturbation with a given initial radial profile.
