Revised cosmological parameters after BICEP 2 and BOSS

Abstract

Estimation of parameters of the 'standard' model of cosmology have dramatically improved over past few decades due to increasingly exquisite measurements made by Cosmic Microwave Background (CMB) experiments. Recent data from Planck matches well with the minimal ΛCDM model. A likelihood analysis using Planck, WMAP and a selection of high resolution experiments (highL), tensor to scalar ratio r_0.002 is found to be < 0.11 when dn_s/d ln k = 0. Planck also imposes an upper bound on neutrino mass ∑ mν< 0.23 eV using Planck + WMAP + highL + BAO likelihood. However, recently results from BICEP 2 claims the detection of r= 0.2^+0.07−0.05 from polarization spectra. Further, results from SDSS-III BOSS large scale galaxy survey constrains the total neutrino mass to ∑ mν=0.36 ± 0.10 eV . It is important to study the consequences of these new measurements on other cosmological parameters. In this paper we assess the revised constraints on cosmological parameters in light of these two measurements that are in some tension with the constraints from Planck. The sensitivity of Planck to weak lensing effect on the CMB angular power spectrum suggests that the normalized amplitude of physical lensing power A_L > 1 at 2σ hints at a potentially important internal inconsistency. Therefore, we also include a study of the constraints on A_L. Using the prior on ∑ mν as measured by SDSS-III BOSS and BICEP 2 likelihood, we find that the model with running spectral index (dn_s/d ln k ≠ 0) leads to a value of AL>1 at 3.1 σ. But, the model with dns/d ln k =0 makes A_L consistent with 1, at 2.1σ and also shows that Neff is consistent with its theoretical value of 3.046 at around 2σ. Therefore, the analysis in this paper shows that the model with dn_s/d ln k =0 gives consistency with other cosmological parameters (N_eff and A_L ) when the current limits on ∑ m_v and r_0.05 are considered. However, on reducing the value of r_0.05, the model with non-zero dn_s/d ln k gives consistent result of A_L =1.