Complementary constraints on non-standard cosmological models from CMB and BBN

We study metric-affine gravity (MAG) inspired cosmological models. Those models were statistically estimated using the SNIa data. We also use the cosmic microwave background observations and the big-bang nucleosynthesis analysis to constrain the density parameter Omega(psi,0) which is related to the non-Riemannian structure of the underlying spacetime. We argue that while the models are statistically admissible from the SNIa analysis, complementary stricter limits obtained from the CMB and BBN indicate that the models with density parameters with a a(-6) scaling behaviour are virtually ruled out. If we assume the validity of the particular MAG based cosmological model throughout all stages of the universe, the parameter estimates from the CMB and BBN put a stronger limit, in comparison to the SNIa data, on the presence of non-Riemannian structures at low redshifts. (c) 2005 Elsevier B.V. All rights reserved.