Dark energy constraints after the new Planck data

Abstract

The Planck Collaboration has recently published maps of the cosmic microwave background radiation with the highest precision. In the standard flat Λ cold dark matter framework, Planck data show that the Hubble constant H₀ is in tension with that measured by the several direct probes on H₀. In this paper, we perform a global analysis from the current observational data in the general dark energy models and find that resolving this tension requires the dark energy model with its equation of state (EOS) w≠-1. Firstly, assuming the w to be a constant, the Planck data favor w<-1 at about 2σ confidence level when combining with the supernovae “supernova legacy survey” compilation. Consequently the value derived on H₀, H₀=71.3±2.0kms^-1Mpc^-1 (68% C.L.) is consistent with that from direct H₀ probes. We then investigate the dark energy model with a time-evolving w, and obtain the 68% C.L. constraints w₀=-0.81±0.19 and w_a=-1.9±1.1 from the Planck data and the “supernova legacy survey” compilation. Current data still slightly favor the quintom dark energy scenario with EOS across the cosmological constant boundary w≡-1.