Dark side of the Universe after Planck data

Abstract

Recently released Planck data imply a smaller Hubble constant H₀ than that from the Hubble Space Telescope project (HST) and a larger percentage of the matter components Ω_m compared to the Supernova Legacy Survey (SNLS) in the Λ _{cold dark matter (CDM) model. In this paper we found that even though the tension on H0} between Planck and HST can be relaxed if the dark radiation is introduced [Δ_Neff=0.536-0.224+0.229 at 68% CL from the data sets of Planck+WMAP polarization (WP)+baryon acoustic oscillation (BAO)+the combination of supernova Union2.1 compilation of 580 Supernovae (Union2.1)+HST], Ω_m from Planck is still not nicely compatible with that from SNLS. The tensions between Planck and other astrophysical data sets can be significantly relaxed in the wCDM model, and the combination of these data sets prefers a phantomlike dark energy at more than 95% CL: w =-1.15±0.07 and w=-1.16±0.06 at 68% CL from Planck+WP+BAO+Union2.1+HST and Planck+WP+BAO+SNLS+HST, respectively. From the statistical point of view, there is no evidence for a time-evolving equation of state (Δχ²=-0.3 compared to a constant equation of state for the combination of Planck+WP+BAO+SNLS+HST).