Observational constraint on dynamical evolution of dark energy

TL;DR

This paper analyzes the evolution of dark energy using multiple observational datasets, finding no significant evidence for evolution in its equation of state, and highlights the impact of different BAO data on results.

Contribution

It provides a model-independent analysis of dark energy evolution using piecewise constant parametrization and compares results with different BAO datasets.

Findings

No significant evolution detected in dark energy equation of state.

Adding Hubble parameter data improves high-redshift constraints by 70%.

Differences in results are linked to variations in matter density parameter m0.

Abstract

We use the Constitution supernova, the baryon acoustic oscillation, the cosmic microwave background, and the Hubble parameter data to analyze the evolution property of dark energy. We obtain different results when we fit different baryon acoustic oscillation data combined with the Constitution supernova data to the Chevallier-Polarski-Linder model. We find that the difference stems from the different values of $\Omega_{m0}$. We also fit the observational data to the model independent piecewise constant parametrization. Four redshift bins with boundaries at $z=0.22$, 0.53, 0.85 and 1.8 were chosen for the piecewise constant parametrization of the equation of state parameter $w(z)$ of dark energy. We find no significant evidence for evolving $w(z)$. With the addition of the Hubble parameter, the constraint on the equation of state parameter at high redshift isimproved by 70%. The marginalization of the nuisance parameter connected to the supernova distance modulus is discussed.