Exploring the deviation of cosmological constant by a generalized pressure parameterization

Jun-Chao Wang,Xin-He Meng

doi:10.1140/epjc/s10052-019-7343-x

Jun-Chao Wang, Xin-He Meng

Open Access

https://doi.org/10.1140/epjc/s10052-019-7343-x

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Abstract

We bring forward a generalized pressure (GP) parameterization for dark energy to explore the evolution of the universe. This parametric model has covered three common pressure parameterization types and can be reconstructed as quintessence and phantom scalar fields, respectively. We adopt the cosmic chronometer (CC) datasets to constrain the parameters. The results show that the inferred late-universe parameters of the GP parameterization are (within 1sigma ): the present value of Hubble constant H_{0}=(72.30^{+1.26}_{-1.37}) hbox {km s}^{-1}hbox { Mpc}^{-1}; the matter density parameter Omega _{text {m0}}=0.302^{+0.046}_{-0.047}, and the bias of the universe towards quintessence. Then we perform a dynamic analysis on the GP parameterization and find that there is an attractor or a saddle point in the system corresponding to the different values of the parameters. Finally, we discuss the ultimate fate of the universe under the phantom scenario in the GP parameterization. It is demonstrated that the three cases of pseudo rip, little rip, and big rip are all possible.

Highlights

The model presented in this paper is a dynamic dark energy model, which parameterizes the total pressure of the universe
Note that when β = −3, the density of the part of the dark energy is expressed as the matter density, and the total density ρ(a) of our generalized pressure (GP) parameterization has the same form as the CDM model
It is interesting to insert models or theories into a more general framework to test their validity. Does this reveal a new set of solutions, but it may enable more accurate consistency checks for the original model

Summary

Introduction

The model presented in this paper is a dynamic dark energy model, which parameterizes the total pressure of the universe. We can write the pressure parameter equation as P = n=0 Pn xn(z), where xn(z) expands for the late universe in the following forms: (i) redshift: xn = zn, (ii) scale factor: xn(z) = (1 − a)n = (z/(1 + z))n, (iii) logarithmic form: xn(z) = (ln(1 + z))n. In order to unify these mainstream parameterization methods, we suggest a three-parameter pressure parameterization model to explore the evolution of the universe. The discussion of fixed points using the GP parameterization is analyzed in Sect.

Theoretical model

Results of the data analysis

Dynamic analysis

Fate of the universe under the phantom field

Conclusions