Concentrated Dark Matter: Enhanced Small-scale Structure from
  Co-Decaying Dark Matter
  We study the cosmological consequences of co-decaying dark matter - a
recently proposed mechanism for depleting the density of dark matter through
the decay of nearly degenerate particles. A generic prediction of this
framework is an early dark matter dominated phase in the history of the
universe, that results in the enhanced growth of dark matter perturbations on
small scales. We compute the duration of the early matter dominated phase and
show that the perturbations are robust against washout from free-streaming. The
enhanced small scale structure is expected to survive today in the form of
compact micro-halos and can lead to significant boost factors for indirect
detection experiments, such as FERMI, where dark matter would appear as point
sources.
