Study of Homogeneous and Isotropic Universe in $f(R,T^{\varphi})$ Gravity

TL;DR

This paper explores the cosmological evolution of a homogeneous, isotropic universe within $f(R,T^{}$ gravity, analyzing scalar field dynamics and showing the model can replicate $ ext{Lambda}$CDM behavior at early and late times.

Contribution

It introduces a first-order formalism approach to $f(R,T^{}$ gravity with scalar fields, analyzing different $W()$ forms and their cosmological implications.

Findings

Identifies phantom era in early universe for some models.

Exponential $W()$ yields constant $$-independent $^{eff}$.

Model reproduces $ ext{Lambda}$CDM$ behavior at initial and late times.

Abstract

This paper is devoted to study the cosmological behavior of homogeneous and isotropic universe model in the context of $f(R,T^{\varphi})$ gravity where $\varphi$ is the scalar field. For this purpose, we follow the first order formalism defined by $H=W(\varphi)$. We evaluate Hubble parameter, effective equation of state parameter $(\omega^{eff})$, deceleration parameter and potential of scalar field for three different values of $W(\varphi)$. We obtain phantom era in some cases for the early times. It is found that exponential expression of $W(\varphi)$ yields $\omega^{eff}$ independent of time for flat universe and independent of model parameter otherwise. It is concluded that our model corresponds to $\Lambda$CDM for both initial as well as late times.