Acceleration in Friedmann cosmology with torsion

Abstract

A Friedmann like cosmological model in Einstein–Cartan framework is studied when the torsion function is assumed to be proportional to a single ϕ(t) function coming just from the spin vector contribution of ordinary matter. By analysing four different types of torsion function written in terms of one, two and three free parameters, we found that a model with ϕ(t) = - αH(t) (ρm(t) / ρc) n is totally compatible with recent cosmological data, where α and n are free parameters to be constrained from observations, ρm is the matter energy density and ρc the critical density. The recent accelerated phase of expansion of the universe is correctly reproduced by the contribution coming from torsion function, with a deceleration parameter indicating a transition redshift of about 0.65.