Accelerating scenarios of viscous fluid universe in modified f(T) gravity.

In this paper, we have investigated the physical behavior of cosmological models in modified teleparallel gravity with a linear function f (T) = α T + β where α and β are model parameters and T is the torsion scalar. We have considered a homogeneous and isotropic Friedman universe filled with bulk viscosity fluid. We have solved the field equations for the scale factor a (τ) and found a (τ) = c 1 [ sinh (n 2 τ) ] n 3 where n 2 = β (1 + ω) [ κ 2 ξ 0 − 3 (1 + ω) (1 + α) ] 8 and n 3 = 2 [ κ 2 ξ 0 − 3 (1 + ω) (1 + α) ] and c 1 is an integrating constant, ω is the equation of state (EoS) for normal matter and ξ 0 is generated from bulk viscosity fluid. We have calculated the several cosmological parameters for this scale factor and studied their physical and geometrical behavior along with the observational data sets H (z) and Union 2. 1 compilation of SNe Ia data sets. We have observed that the β factor reveals the presence of cosmological constant and for β = 0 , the acceleration drives by the bulk viscosity of the fluid and it behaves just like dark energy model without cosmological constant. We have studied the effective EoS ω eff and found − 0. 2 8 0 7 ≤ ω eff ≤ − 0. 1 7 6 0. We have evaluated the age of the present universe as 1 3. 8 7 Gyrs. Also, we have studied the nature of deceleration parameter with the signature-flipping point at z t = 0. 5 , 1. 1 4 and the present value of deceleration parameter q 0 is obtained as − 0. 3 3 0 3 , − 0. 4 1 5 2 , respectively, for both observational datasets. [ABSTRACT FROM AUTHOR]