Spinning fluid cosmologies in Einstein-Cartan theory

Abstract

We consider self-consistent spinning fluid cosmologies in both general relativity in Riemannian spacetimes and Einstein-Cartan theory in Riemann-Cartan spacetimes. First we extend slightly the cosmological calculation of Martin et al for general relativistic self-consistent spinning fluids. The existence of spin-squared terms in the field equations in the Einstein-Cartan theory shows, however, that an expanded class of meaningful cosmologies is possible. Under certain assumptions on the arbitrariness of the cosmological shear and expansion the results for the ad hoc Weyssenhoff spin fluid in a spherically symmetric spacetime can be reproduced.