Primordial Non-Gaussianity and Reionization
  The statistical properties of the primordial perturbations contain clues
about the origins of those fluctuations. Although the Planck collaboration has
recently obtained tight constraints on primordial non-gaussianity from cosmic
microwave background measurements, it is still worthwhile to mine upcoming data
sets in effort to place independent or competitive limits. The ionized bubbles
that formed at redshift z~6-20 during the Epoch of Reionization are seeded by
primordial overdensities, and so the statistics of the ionization field at high
redshift are related to the statistics of the primordial field. Here we model
the effect of primordial non-gaussianity on the reionization field. The epoch
and duration of reionization are affected as are the sizes of the ionized
bubbles, but these changes are degenerate with variations in the properties of
the ionizing sources and the surrounding intergalactic medium. A more promising
signature is the power spectrum of the spatial fluctuations in the ionization
field, which may be probed by upcoming 21 cm surveys. This has the expected
1/k^2 dependence on large scales, characteristic of a biased tracer of the
matter field. We project how well upcoming 21 cm observations will be able to
disentangle this signal from foreground contamination. Although foreground
cleaning inevitably removes the large-scale modes most impacted by primordial
non-gaussianity, we find that primordial non-gaussianity can be separated from
foreground contamination for a narrow range of length scales. In principle,
futuristic redshifted 21 cm surveys may allow constraints competitive with
Planck.
