Phantom dark energy nature of bulk-viscosity universe in modified f(Q)-gravity

Abstract

This paper deals with an anisotropic cosmological model in the modified theory of [Formula: see text]-gravity filled with bulk-viscosity fluid. We investigated the modified [Formula: see text]-gravity with quadratic form [Formula: see text], where [Formula: see text] is the non-metricity scalar and [Formula: see text] is a positive constant, in Locally-Rotationally Symmetric (LRS) Bianchi type-[Formula: see text] space time universe. We have solved the modified Einstein’s field equations with bulk-viscosity factor [Formula: see text] and obtained average scale factor [Formula: see text] where [Formula: see text] is a constant and [Formula: see text], and [Formula: see text]. We have investigated the model in two cases [Formula: see text] and [Formula: see text]. We have found the best-fit values of model parameters with observational datasets like Union 2.1 compilation and Joint Light Curve Analysis (JLA) datasets by applying [Formula: see text]-test formula in curve-fitting. Using these best-fit values of model parameters, we have studied the cosmological parameter like Hubble parameter [Formula: see text] and deceleration parameter [Formula: see text], equation of state (EoS) parameter, age of the present universe [Formula: see text], etc. We have obtained a transit model (i.e. decelerating to accelerating in current) in the first case [Formula: see text] and a transit phase model from accelerating to decelerating in the second case [Formula: see text]. We have investigated the EoS parameter [Formula: see text] for bulk-viscosity and obtained the present values as [Formula: see text], which is supported by the observational results. We have also analyzed energy conditions and statefinder parameters and found that our model approaches to LCDM model in the future.