Torsion cosmology of Poincaré gauge theory and the constraints of its parameters via SNeIa data

Poincarè gauge theory (PGT) is an alternative gravity theory, which brings the gravity into the gauge-theoretic framework, where the Lagrangian includes both quadratic torsion and curvature terms. Recently, the cosmological models with torsion based on this theory, which explained the cosmic acceleration in a new way, have received much attention. Among these PGT cosmological models, the one with only even parity dynamical modes-SNY model, for its realistic meaning, is very attractive. In this paper, we first analyze the past-time cosmic evolution of SNY model analytically. And based on these results we fit this model to the most comprehensive SNeIa data (Union 2) and thus find the best-fit values of model parameters and initial conditions, whose related χ² value is consistent with the one from ΛCMD at the 1σ level. Also by the χ² estimate, we provide certain constraints on these parameters. Using these best-fit values for the Union 2 SNeIa dataset, we are able to predict the evolution of our real universe in late time. From this prediction, we know that the fate of our universe is that it would expand forever, slowly asymptotically to a halt, which is in accordance with the earlier works.