Reconstructing cosmic evolution with a density parametrization

Abstract

This study examines a dark energy cosmological model in the classical domain, where a generic scalar field is considered a dark energy source. Einstein’s field equations are solved in a model independent way, i.e. using a scheme of cosmological parametrization. A simple parametrization of the density parameter as a function of the cosmic scale factor is considered and investigated extensively. The results obtained are noteworthy as it shows a smooth transition from a decelerating to an accelerating phase in the recent past. Certain external datasets are used here to limit the model parameters involved in the functional form of the considered parametrization of energy density of the scalar filed. The updated Hubble datasets containing 57 data points, 1048 points of recently compiled Pantheon datasets, and also the Baryon Acoustic Oscillation (BAO) datasets are used here to determine the best-fitting model parameter values. The expressions of several significant cosmological parameters are represented as a function of redshift “[Formula: see text]” and illustrated visually for the best fit values of the model parameters to better comprehend cosmic evolution. The obtained model is also compared with the [Formula: see text]CDM model. Our model has a distinct behavior in future and shown a big crunch type collapse. The best fit values of the model parameters are also used to compute the current values of several physical and geometrical parameters, as well as phase transition redshift. To examine the nature of dark energy, certain cosmological tests and diagnostic analyses are done on the derived model.