Constraints on parameterized dark energy properties from new observations with principal component analysis

Abstract

For dark energy, the equation of state (EoS) is a critical parameter to depict its physical properties. In this paper, we mainly give constraints on the EoS of dark energy w with the latest observations of cosmic microwave background radiation (CMB) from Planck satellite, JLA Type Ia supernovae (SNIa) sample, baryon acoustic oscillation (BAO) and Hubble parameter measurements. We introduce a kind of parameterized dark energy model called “constant bin−w”, in which the whole redshift range is divided into several bins, and EoS w in each bin is assumed as an independent constant. The results show that EoS in all of the redshift bins are comparable with ΛCDM in the 2σ confidence regions, but some weak deviations from w=−1 are still indicated. In particular, in the framework of 7 bins, a slight oscillation behavior is shown in the redshift 0 < z < 0.75, especially around the range of 4th bin (0.25 < z < 0.35) and 5th bin (0.35 < z < 0.51). Additionally, we adopt the principal component analysis (PCA) method to do the model-independent analysis, which includes normal PCA and localized PCA methods. By implementing so called normal PCA method, the original oscillation behavior of EoS indicated in the framework of 7 bins becomes more significant after the best reconstruction, but such result still supports ΛCDM within the margin of 2σ errors. To further reduce the errors of constraints on EoS, and confirm such deviations from the cosmological constant scenario, we hope for more precise observational data in the future.