A new search for features in the primordial power spectrum

We develop a new approach towards a high-resolution non-parametric reconstruction of the primordial power spectrum using the Wilkinson Microwave Anisotropy Probe (WMAP) cosmic microwave background temperature anisotropies that we confront with Sloan Digital Sky Survey large-scale structure data in the range k∼ 0.01–0.1 h Mpc−1. We utilize the standard Λ cold dark matter cosmological model but we allow the baryon fraction to vary. In particular, for the concordance baryon fraction, we compare indications of a possible feature at k∼ 0.05 h Mpc−1 in WMAP data with suggestions of similar features in large-scale structure surveys.