Cosmological Density Perturbations in two fluid models on spin dominated inflation and the stability of Friedmann metric

Abstract

A spinning fluid embedded in a space section flat Friedmann model is used to compute the cosmological density perturbation of the model.The spinning fluid obeys the Einstein-Cartan field equations while the Friedmann embedded model is assumed to obey the general the Friedmann equation in General Relativity.It is shown that at the early epochs of the Universe the spin-torsion contribution to the density perturbation on the matter phase dominates over the radiation perturbation.On the other hand at the present epochs of the Universe the spin-torsion contribution is more efficient in the matter perturbation.Stability of the Friedmann solution in Einstein-Cartan cosmology is also discussed.