Scalar field and time varying Cosmological constant in $f(R,T)$ gravity for Bianchi type-I Universe

TL;DR

This paper investigates scalar fields and a time-varying cosmological constant within an $f(R,T)$ gravity framework for Bianchi type-I universes, analyzing power law and exponential volume expansion models with observationally consistent results.

Contribution

It introduces specific $f(R,T)$ models with scalar fields and cosmological constants in anisotropic Bianchi type-I universes, exploring their physical properties and compatibility with observations.

Findings

Power law models support both quintessence and phantom scalar fields.

Exponential models support only quintessence scalar fields.

Cosmological constant values align with observational data.

Abstract

In this article, we have analysed the behaviour of scalar field and cosmological constant in $f(R,T)$ theory of gravity. Here, we have considered the simplest form of $f(R,T)$ i.e. $f(R,T)=R+2f(T)$, where $R$ is the Ricci scalar and $T$ is the trace of the energy momentum tensor and explored the spatially homogeneous and anisotropic Locally Rotationally Symmetric (LRS) Bianchi type-I cosmological model. It is assumed that the Universe is filled with two non-interacting matter sources namely scalar field (normal or phantom) with scalar potential and matter contribution due to $f(R,T)$ action. We have discussed two cosmological models according to power law and exponential law of the volume expansion along with constant and exponential scalar potential as sub models. Power law models are compatible with normal (quintessence) and phantom scalar field whereas exponential volume expansion models are compatible with only normal (quintessence) scalar field. The values of cosmological constant in our models are in agreement with the observational results. Finally, we have discussed some physical and kinematical properties of both the models.