A stable flat universe with variable Cosmological constant in f(R,T) Gravity

TL;DR

This paper develops a cosmological model within f(R,T) gravity featuring a variable cosmological constant, exploring solutions that describe both decelerating and accelerating flat universes, including stable accelerating solutions with negative cosmological constant.

Contribution

It introduces a new cosmological model in f(R,T) gravity with a variable cosmological constant and analyzes its solutions for different deceleration parameters.

Findings

Stable flat decelerating universe at q=1

Stable accelerating universe with negative cosmological constant

Possible explanation for late-time acceleration mechanisms

Abstract

In this paper, a general FRW cosmological model has been constructed in $f(R,T)$ gravity reconstruction with variable cosmological constant. A number of solutions to the field equations has been generated by utilizing a form for the Hubble parameter that leads to Berman's law of constant deceleration parameter $q=m-1$. The possible decelerating and accelerating solutions have been investigated. For ($q>0$) we get a stable flat decelerating radiation-dominated universe at $q=1$. For ($q<0$) we get a stable accelerating solution describing a flat universe with positive energy density and negative cosmological constant. Nonconventional mechanisms that are expected to address the late-time acceleration with negative cosmological constant have been discussed.