Cosmological Analysis of $f(R, \Sigma, T)$ Gravity with EoS Parameterization

TL;DR

This paper investigates a modified gravity model with nonlinear matter-geometry coupling, constrains its parameters using observational Hubble data, and finds it consistent with standard cosmology while allowing slight deviations, supporting its viability for explaining cosmic acceleration.

Contribution

It introduces a new $f(R, \, \Sigma, \, T)$ gravity model with CPL EoS parameterization and constrains it with observational data, demonstrating its consistency with $\\Lambda$CDM and observational bounds.

Findings

Model aligns with $\\Lambda$CDM within observational limits.

Constraints on model parameters are tight and consistent with data.

Universe age estimate matches Planck 2018 results.

Abstract

In this paper, we present a comprehensive cosmological analysis within the framework of $f(R, \Sigma, T)$ gravity, a modified theory that incorporates nonlinear matter-geometry coupling via the inclusion of both the trace of the energy-momentum tensor $T$ and the scalar $\Sigma = T_{\mu\nu}T^{\mu\nu}$. We consider a spatially flat Friedmann-Robertson-Walker (FRW) universe and introduce a linear parameterization for the equation of state (EoS) parameter based on the Chevallier-Polarski-Linder (CPL) form, which allows us to explore the dynamical evolution of dark energy without imposing restrictive assumptions. To confront the theoretical model with observations, we utilize the latest Hubble parameter measurements from cosmic chronometers. The model parameters are constrained using Markov Chain Monte Carlo (MCMC) simulations with the \texttt{emcee} package, leading to tight bounds on the parameters. The analysis reveals that the model remains consistent with the $\Lambda$CDM scenario while allowing mild deviations consistent with observational data. Furthermore, we examine the physical and kinematical features of the model by studying the behavior of the physical parameters. Finally, the calculated age of the universe within this framework is found to be in excellent agreement with Planck 2018 results, highlighting the and viability of $f(R, \Sigma, T)$ gravity as a candidate for explaining late-time cosmic acceleration.