Bulk viscous fluid in extended symmetric teleparallel gravity

Abstract

In this paper, we investigate the existence of bulk viscous FLRW cosmological models in a recently proposed extended symmetric teleparallel gravity or fQ,T gravity in which Q is the non-metricity and T is the trace of the energy–momentum tensor. We consider a simple coupling between matter and non-metricity, specifically, fQ,T=αQm+1+λT and fQ,T=αQ+λT where α, λ and m are free model parameters. The exact cosmological solutions are found by assuming the scale factor in the form of the hybrid expansion law. This type of relation generates a time-varying deceleration parameter with the transition of the Universe from the early decelerating phase to the present accelerating phase. In the presence of viscous fluid, we analyze some cosmological parameters of our cosmological model such as the energy density, bulk viscous pressure, bulk viscous coefficient, equation of state parameter, and energy conditions. Finally, we conclude our fQ,T cosmological models agree with the recent astronomical observations.