Seeking Evolution of Dark Energy

TL;DR

This paper investigates methods to distinguish between a cosmological constant and evolving dark energy by analyzing the redshift at which cosmic acceleration begins, proposing that precise measurements of this transition could clarify dark energy's nature.

Contribution

It introduces a new approach focusing on the redshift where cosmic acceleration starts, including a novel model that better describes the entire expansion history.

Findings

Z* = 0.743 with 4% error for CC models

Potential for model-independent measurement of Z*

Implications for understanding dark energy evolution

Abstract

We study how observationally to distinguish between a cosmological constant (CC) and an evolving dark energy with equation of state $\omega(Z)$. We focus on the value of redshift Z* at which the cosmic late time acceleration begins and $\ddot{a}(Z^{*}) = 0$. Four $\omega(Z)$ are studied, including the well-known CPL model and a new model that has advantages when describing the entire expansion era. If dark energy is represented by a CC model with $\omega \equiv -1$, the present ranges for $\Omega_{\Lambda}(t_0)$ and $\Omega_m(t_0)$ imply that Z* = 0.743 with 4% error. We discuss the possible implications of a model independent measurement of Z* with better accuracy.