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

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.

19 pages, 18 figures