Parametrization Framework for the Deceleration Parameter in Scalar Field Dark Energy Model

TL;DR

This paper introduces a new parametrization of the deceleration parameter in a scalar field dark energy model, constrained by recent observational data, to better understand the universe's expansion history and the nature of dark energy.

Contribution

A novel parametrization of the deceleration parameter is proposed and constrained using observational data, offering a model-independent framework to study dark energy dynamics.

Findings

The model fits well with observational data.

It provides insights into the transition from deceleration to acceleration.

Comparison with ΛCDM shows competitive performance.

Abstract

We propose a Friedmann-Lemaitre-Robertson-Walker cosmological model with a scalar field that represents dark energy. A new parametrization of the deceleration parameter is introduced of the form $q = 1 + \eta (1 + \mu a^{\eta})$ where $\eta$ and $\mu$ are model parameters. and the compatibility of the model is constrained by recent observational datasets, including cosmic chronometers, Pantheon+ and Baryon Acoustic Observations. By considering a variable deceleration parameter, we address the expansion history of the universe, providing a viable description of the transition from deceleration to acceleration. Using the Markov Chain Monte Carlo method, the parameters of the model are constrained and we examine the cosmological parameters. A comparison is then made with the $\Lambda$CDM model using the latest observations. We examine the history of the main cosmological parameters, such as the deceleration parameter, jerk parameter, snap parameter, density parameter, and equation-of-state parameter, by constraining and interpreting them to reveal insights into what has been dubbed "dynamical dark energy" under the assumptions made above. Our method provides a framework that is independent of the model to explore dark energy, leading to a deeper and more subtle understanding of the mechanisms driving late-time cosmic acceleration.