Probing the dynamics of dark energy with novel parametrizations

TL;DR

This paper introduces two new dark energy parametrizations that avoid divergence issues of previous models, enabling comprehensive analysis of dark energy dynamics and universe fate with observational data.

Contribution

The paper proposes two novel, divergence-free parametrizations for dark energy, improving upon the CPL model for analyzing the universe's entire evolutionary history.

Findings

New models successfully avoid future divergence problems.

New parametrizations are more favored by current observational data.

Models provide detailed predictions for the universe's future evolution.

Abstract

We point out that the CPL parametrization has a problem that the equation of state $w(z)$ diverges in the far future, so that this model can only properly describe the past evolution but cannot depict the future evolution. To overcome such a difficulty, in this Letter we propose two novel parametrizations for dark energy, the logarithm form $w(z)=w_0+w_1({\ln (2+z)\over 1+z}-\ln2)$ and the oscillating form $w(z)=w_0+w_1({\sin(1+z)\over 1+z}-\sin(1))$, successfully avoiding the future divergency problem in the CPL parametrization, and use them to probe the dynamics of dark energy in the whole evolutionary history. Our divergency-free parametrizations are proven to be very successful in exploring the dynamical evolution of dark energy and have powerful prediction capability for the ultimate fate of the universe. Constraining the CPL model and the new models with the current observational data, we show that the new models are more favored. The features and the predictions for the future evolution in the new models are discussed in detail.