Dark Energy Models With Variable Equation Of State Parameter

TL;DR

This paper investigates two variable Lambda cosmological models with a time-dependent equation of state parameter, demonstrating their equivalence in different dimensions and exploring the deceleration parameter's signature flip.

Contribution

It introduces and compares two variable Lambda models with a dynamic equation of state, highlighting their equivalence and cosmological implications.

Findings

Models are equivalent in four and five dimensions.

Deceleration parameter can undergo a signature flip.

Variable Lambda models are consistent with cosmological observations.

Abstract

Two variable $\Lambda$ models, viz. $\Lambda \sim (\dot a/a)^2$ and $\Lambda \sim \rho$ have been studied under the assumption that the equation of state parameter $\omega$ is a function of time. The selected $\Lambda$ models are found to be equivalent both in four and five dimensions. The possibility of signature flip of the deceleration parameter is also shown.