Inflation wars: a new hope

Abstract

We explore a class of primordial power spectra that can fit the observed anisotropies in the cosmic microwave background well and that predicts a value for the Hubble parameter consistent with the local measurement of H0 = 74 km/s/Mpc. This class of primordial power spectrum consists of a continuous deformation between the best-fit power law primordial power spectrum and the primordial power spectrum derived from the modified Richardson-Lucy deconvolution algorithm applied to the Cℓs of best-fit power law primordial power spectrum. We find that linear interpolation half-way between the power law and modified Richardson-Lucy power spectra fits the Planck data better than the best-fit ΛCDM by Δ log Script L = 2.5. In effect, this class of deformations of the primordial power spectra offer a new dimension which is correlated with the Hubble parameter. This correlation causes the best-fit value for H0 to shift and the uncertainty to expand to H0 = 70.2 ± 1.2 km/s/Mpc. When considering the Planck dataset combined with the Cepheid H0 measurement, the best-fit H0 becomes H0 = 71.8 ± 0.9 km/s/Mpc. We also compute a Bayes factor of log K = 5.7 in favor of the deformation model.