Reconstructing primordial power spectrum using Planck and SDSS-III measurements

TL;DR

This paper introduces a Bayesian method for reconstructing the primordial power spectrum from multiple cosmological data sets, revealing deviations from scale invariance and suggesting possible features on large scales.

Contribution

A new model-independent Bayesian approach for primordial power spectrum reconstruction applied to diverse cosmological data sets.

Findings

Scale-invariant spectrum strongly disfavored

Suppressed power on horizon scales supported by data

Mild evidence for a modulation on specific scales

Abstract

We develop an accurate and efficient Bayesian method to reconstruct the primordial power spectrum in a model-independent way, and apply it to the latest cosmic microwave background measurement from Planck mission, and the large scale structure observation of SDSS-III BOSS (CMASS) sample, combined with the type Ia supernovae sample (SNLS 3-year) and the measurements of baryon acoustic oscillations from SDSS-II, 6dF, and WiggleZ survey. We confirm that the scale-invariant primordial power spectrum is strongly disfavored, and a model with suppressed power on horizon scales is supported by current data. We also find that a modulation on scales $5\times10^{-4}~\textrm{Mpc}^{-1} \lesssim k \lesssim 0.01~\textrm{Mpc}^{-1}$ is mildly preferred at $2\sigma$ confidence level, whose origin needs further investigation.