CMB anisotropies from acausal scaling seeds
  We investigate models where structure formation is initiated by scaling
seeds: We consider rapidly expanding relativistic shells of energy and show
that they can fit current CMB and large scale structure data if they expand
with super-luminal velocities. These acausally expanding shells provide a
viable alternative to inflation for cosmological structure formation with the
same minimal number of parameters to characterize the initial fluctuations.
Causally expanding shells alone cannot fit present data. Hybrid models where
causal shells and inflation are mixed also provide good fits.
