Constraining the dynamical dark energy parameters: Planck-2013 vs WMAP9

Abstract

We determine the best-fit values and confidence limits for dynamical dark energy parameters together with other cosmological parameters on the basis of different datasets which include WMAP9 or Planck-2013 results on CMB anisotropy, BAO distance ratios from recent galaxy surveys, magnitude-redshift relations for distant SNe Ia from SNLS3 and Union2.1 samples and the HST determination of the Hubble constant. We use a Markov Chain Monte Carlo routine to map out the likelihood in the multi-dimensional parameter space. We show that the most precise determination of cosmological parameters with the narrowest confidence limits is obtained for the Planck+HST+BAO+SNLS3 dataset. The best-fit values and 2σ confidence limits for cosmological parameters in this case are Ω_de = 0.718±0.022, w₀ = -1.15^+0.14_-0.16, c_a² = -1.15^+0.02_-0.46, Ω_bh² = 0.0220±0.0005, Ω_cdmh² = 0.121±0.004, h = 0.713±0.027, n_s = 0.958^+0.014_-0.010, A_s = (2.215^+0.093_-0.101)ṡ10^-9, τ_rei = 0.093^+0.022_-0.028. For this dataset, the ΛCDM model is just outside the 2σ confidence region, while for the dataset WMAP9+HST+BAO+SNLS3 the ΛCDM model is only 1σ away from the best fit. The tension in the determination of some cosmological parameters on the basis of two CMB datasets WMAP9 and Planck-2013 is highlighted.