Quintom-like transit universe models in Metric-affine $f(R,T,Q,T_m)$ gravity

TL;DR

This paper explores a new class of cosmological models within metric-affine $f(R,T,Q,T_m)$ gravity, deriving solutions that fit observational data and exhibit quintom-like dark energy behavior.

Contribution

It introduces and analyzes a novel $f(R,T,Q,T_m)$ gravity model with hyperbolic solutions and observational constraints, extending general relativity with additional geometric scalars.

Findings

Model fits observational data well

Exhibits phantom and quintom dark energy behavior

Predicts a universe with quintom-A characteristics

Abstract

The current transit universe model is a precise solution to the equations of a new type of gravity theory called metric-affine $f(R,T,Q,T_m)$ gravity proposed in [Herko et al. \textit{Phys. Dark Univ.} \textbf{34} (2021) 100886]. This theory is the maximal extension of the most successful theory, ``General Relativity," by including the scalars, Ricci curvature $R$, torsion $T$, nonmetricity $Q$, and trace $T_{m}$ of the matter-energy-momentum tensor using a generalized connection called the ``metric-affine" connection. We obtain the modified field equations for a linear form of the $f(R,T,Q,T_m)$ function and for a flat, homogeneous, and isotropic FLRW spacetime universe. We find a hyperbolic solution and determine the constrained values of the model parameters using the latest observational data. We examine how certain cosmological factors, like the deceleration parameter $q(z)$, effective equation of state parameter $\omega_{\rm eff}$, and dark energy equation of state parameter $\omega_{\rm de}$, vary over time to explain the properties of the observable universe. We perform the $Om$ diagnostic test for the model, and it represents the phantom scenarios of the model. The behavior of the dark energy EoS parameter $\omega_{\rm de}$ reveals the quintom-A-type universe characteristics.