Confronting the concordance model of cosmology with Planck data

Abstract

We confront the concordance (standard) model of cosmology, the spatially flat ΛCDM Universe with power-lawform of the primordial spectrum with Planck CMB angular power spectrum data searching for possible smoothdeviations beyond the flexibility of the standard model. The departure from the concordance cosmology ismodeled in the context of Crossing statistic and statistical significance of this deviation is used as ameasure to test the consistency of the standard model to the Planck data.Derived Crossing functions suggest the presence of some broad features in angular spectrum beyond the expectations of the concordance model.Our results indicate that the concordance model of cosmology is consistent to the Planck data only at 2 to 3σ confidence levelif we allow smooth deviations from the angular power spectrum given by the concordance model.This might be due to random fluctuations or may hint towards smooth features in the primordial spectrum or departure from another aspect of the standard model.Best fit Crossing functions indicate that there are lack of power in the data at both low-ℓ and high-ℓ with respect to the concordance model. This hints that we mayneed some modifications in the foreground modeling to resolve the significant inconsistency at high-ℓ. However, presence ofsome systematics at high-ℓ might be another reason for the deviation we found in our analysis.