Red, Straight, no bends: primordial power spectrum reconstruction from CMB and large-scale structure

Understand

We present a minimally parametric, model independent reconstruction of the shape of the primordial power spectrum.

• Our smoothing spline technique is well-suited to search for smooth features such as deviations from scale invariance, and deviations from a power law such as running of the spectral index or small-scale power suppression.
• We use a comprehensive set of the state-of the art cosmological data: {\it Planck} observations of the temperature and polarisation anisotropies of the cosmic microwave background, WiggleZ and Sloan Digital Sky Survey Data Release 7 galaxy power spectra and the Canada-France-Hawaii Lensing Survey correlation function.
• This reconstruction strongly supports the evidence for a power law primordial power spectrum with a red tilt and disfavours deviations from a power law power spectrum including small-scale power suppression such as that induced by significantly massive neutrinos.