Cosmic reverberations on a constrained $ f(Q,T) $-model of the Universe

TL;DR

This paper develops an $f(Q,T)$ gravity model that explains the universe's transition from deceleration to acceleration, fitting observational data and addressing the Hubble tension, while proposing a non-traditional Big Bang scenario.

Contribution

It introduces a quadratic $f(Q,T)$ gravity model constrained by recent observations, incorporating an ekpyrotic phase and a non-beginning Big Bang, advancing cosmological modeling.

Findings

Model fits observational datasets well.

Reduces the $H_0$ tension.

Describes a universe with an ekpyrotic phase and late-time quintessence.

Abstract

In this paper, we construct an isotropic cosmological model in the $ f(Q, T) $ theory of gravity in the frame of a flat FLRW spacetime being $ Q $ the non-metricity tensor and $ T $ the trace of the energy-momentum tensor. The gravity function is taken to be a quadratic equation, $ f(Q, T)=\zeta Q^2 + \gamma T $, where $ \zeta<0 $ and $ \gamma $ are the arbitrary constants. We constrain the model parameters $ \alpha $ and $ H_0 $ using the recent observational datasets: the Hubble dataset (OHD), the $ Pantheon $ dataset of $ 1048 $ points, and the joint dataset (OHD + $ Pantheon $). The universe model transitions from an early deceleration state to an acceleration in late times. This model also provides the ekpyrotic phase of the universe on the redshift $ z>12.32 $. In this model, the Big Bang is described as a collision of branes, and thus, the Big Bang is not the beginning of time. Before the Big Bang, there is an ekpyrotic phase with the equation of state $ \omega >> 1 $. In late times, the undeviating Hubble measurements reduce the $ H_0 $ tension in the reconstructed $ f(Q, T) $ function. Additionally, we study various physical parameters of the model. Finally, our model describes a quintessence dark energy model at later times.