An Accelerating Cosmological Model from a Parametrization of Hubble Parameter

TL;DR

This paper proposes a new cosmological model with a parametrized Hubble parameter that explains late-time cosmic acceleration, deriving exact solutions and fitting observational data to support its viability.

Contribution

It introduces a simple parametrization of the Hubble parameter leading to an exponential evolution of the universe and fits observational data to constrain model parameters.

Findings

Model exhibits transition from deceleration to acceleration.

Exact solutions derived for homogeneous isotropic universe.

Model parameters constrained with observational Hubble data.

Abstract

In view of late-time cosmic acceleration, a dark energy cosmological model is revisited wherein Einstein's cosmological constant is considered as a candidate of dark energy. Exact solution of Einstein field equations (EFEs) is derived in a homogeneous isotropic background in classical general relativity. The solution procedure is adopted, in a model independent way (or the cosmological parametrization). A simple parametrization of the Hubble parameter (H) as a function of cosmic time `t' is considered which produces an exponential type of evolution of the scale factor (a) and also shows a negative value of deceleration parameter at the present time with a signature flip from early deceleration to late acceleration. Cosmological dynamics of the model obtained have been discussed illustratively for different phases of the evolution of the universe. The evolution of different cosmological parameters are shown graphically for at and closed cases of Friedmann-Lemaitre-Robertson-Walker (FLRW) space-time for the presented model (open case is incompatible to the present scenario). We have also constrained our model parameters with the updated (36 points) observational Hubble dataset.