Dynamical system method of viscous fluid in f(T) gravity theory

Abstract

In this paper, using the recently introduced f(T) gravity framework, we have analyzed the viscous fluid cosmological model in FLRW cosmological model by assuming a specific form of the bulk viscosity coefficient as, ζ=ζ0+ζ1H+ζ2ḢH+H and a non-linear f(T) model particularly, f(T)=T−α−T where α is the model parameter. The bulk viscosity coefficients are estimated by using Hubble 31 data set. Using the phase space technique, we examine the asymptotic behaviour of our cosmological bulk viscous model. We found one stable critical point. Phase space analysis and the geometrical interpretations are given. We discover that according to our model, the Universe evolved from a matter-dominated decelerated phase (a past attractor) to a stable de-Sitter accelerated epoch (a future attractor). The evolution of EoS parameter shows the acceleration phase of the cosmic expansion whereas the negative behavior of viscosity-induced pressure indicates the accelerated expansion of the Universe. Additionally, the cosmic matter-energy density exhibits positive behavior. We look into how statefinder parameters behave for our model . We discover that the trajectory of our model starts at the quintessence and ends at the ΛCDM region. We use the Om diagnostic test, which reveals that our model displays quintessence behaviour. The energy condition criteria are analyzed, and we discover that SEC has been violated, whereas WEC, NEC and DEC satisfy the positivity criteria. Our f(T) cosmological model, with the influence of bulk viscosity successfully describes the expansion history of the Universe and provides a good fit to recent observational data.