Generalized Phenomenological Models of Dark Energy

Abstract

It was first observed at the end of the last century that the universe is presently accelerating. Ever since, there have been several attempts to explain this observation theoretically. There are two possible approaches. The more conventional one is to modify the matter part of the Einstein Field Equations and the second one is to modify the geometry part. We shall consider two phenomenological models based on the former, more conventional approach within the context of General Relativity. The phenomenological models in this paper consider a Λ term as a function of a a and ρ where a and ρ are the scale factor and matter-energy density respectively. Constraining the free parameters of the models with latest observational data gives satisfactory values of parameters as considered by us initially. Without any field-theoretic interpretation, we explain the recent observations with a dynamical cosmological constant.

Phenomenological dark energy model with hybrid dynamic cosmological constant

“…In particular, we will choose three such expressions of Λ for the present work which are frequently used in literature [16]: 4…”

“…,(9)Substituting (9) in (3) and setting k = 0 for Flat Universe, we get:4 Check the references within[16] for different works done with these three types of models.…”

Iron Technology and Urbanization in Odisha

“…Mishra et al [18] and Ray et al [19] studied the two fluid cosmological models in anisotropic space-time with the energy momentum tensor as the combination of DE fluid and ordinary matter fluid. Without any field theoretic interpretation, Paul and Sengupta [20] have explained the recent observations with a dynamical cosmological constant. Akarsu et al [21] have studied the cosmological constant in the standard ΛCDM model by introducing the graduated DE.…”