Probing kinematics and fate of the Universe with linearly time-varying deceleration parameter

TL;DR

This paper introduces a new linearly time-varying deceleration parameter model for the Universe, compares it with existing models, and analyzes its consistency with observational data to understand cosmic kinematics and fate.

Contribution

It proposes a novel deceleration parameter parametrization linear in cosmic time and compares its implications with established models using observational data.

Findings

The new model fits observational data well.

It provides insights into the Universe's future evolution.

Comparison with bcb5CDM highlights differences in cosmic dynamics.

Abstract

The parametrizations $q=q_0+q_1 z$ and $q=q_0+q_1 (1-a/a_0)$ (Chevallier-Polarski-Linder parametrization) of deceleration parameter, which are linear in cosmic redshift $z$ and scale factor $a$, have been frequently utilized in the literature to study kinematics of Universe. In this paper, we follow a strategy that leads to these two well known parametrizations of deceleration parameter as well as an additional new parametrization $q=q_0+q_1(1-t/t_0)$, which is linear in cosmic time $t$. We study the features of this linearly time-varying deceleration parameter in contrast with the other two linear parametrizations. We investigate in detail the kinematics of the Universe by confronting the three models with the latest observational data. We further study the dynamics of the Universe by considering the linearly time-varying deceleration parameter model in comparison with the standard $\Lambda$CDM model. We also discuss future of the Universe in the context of the models under consideration.