Minimally Parametric Power Spectrum Reconstruction from the Lyman-alpha
  Forest
  Current results from the Lyman alpha forest assume that the primordial power
spectrum of density perturbations follows a simple power law form, with
running. We present the first analysis of Lyman alpha data to study the effect
of relaxing this strong assumption on primordial and astrophysical constraints.
We perform a large suite of numerical simulations, using them to calibrate a
minimally parametric framework for describing the power spectrum. Combined with
cross-validation, a statistical technique which prevents over-fitting of the
data, this framework allows us to reconstruct the power spectrum shape without
strong prior assumptions. We find no evidence for deviation from
scale-invariance; our analysis also shows that current Lyman alpha data do not
have sufficient statistical power to robustly probe the shape of the power
spectrum at these scales. In contrast, the ongoing Baryon Oscillation Sky
Survey (BOSS) will be able to do so with high precision. Furthermore, this
near-future data will be able to break degeneracies between the power spectrum
shape and astrophysical parameters.
