Constraints of the equation of state of dark energy from current and future observational data by piecewise parametrizations

TL;DR

This paper uses piecewise spline methods to analyze current and future observational data, revealing limitations in constraining dark energy's equation of state at higher redshifts and suggesting possible rapid transitions around redshift 0.5.

Contribution

It introduces and compares three spline-based, model-independent methods to constrain dark energy's equation of state from observational data.

Findings

Current data poorly constrains $w_{de}$ beyond redshift 0.5.

Future supernova data will have limited ability to constrain $w_{de}$ beyond redshift 1.

Potential rapid transition of $w_{de}$ around redshift 0.5 detected.

Abstract

The model-independent piecewise parametrizations (0-spline, linear-spline and cubic-spline) are used to estimate constraints of equation of state of dark energy ($w_{de}$) from current observational data (including SNIa, BAO and Hubble parameter) and the simulated future data. A combination of fitting results of $w_{de}$ from these three spline methods reveal essential properties of real equation of state $w_{de}$. It is shown that $w_{de}$ beyond redshift $z\sim0.5$ is poorly constrained from current data, and the mock future $\sim2300$ supernovae data give poor constraints of $w_{de}$ beyond $z\sim1$. The fitting results also indicate that there might exist a rapid transition of $w_{de}$ around $z\sim0.5$. The difference between three spline methods in reconstructing and constraining $w_{de}$ has also been discussed.