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

Adam Krawiec,Marek Szydłowski,Włodzimierz Godłowski

doi:10.1016/j.physletb.2005.05.060

Adam Krawiec, Marek Szydłowski + Show 1 more

Open Access

https://doi.org/10.1016/j.physletb.2005.05.060

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Journal: Physics Letters B	Publication Date: Jun 2, 2005
Citations: 10	License type: cc-by

Affiliation: Jagiellonian University

Abstract

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 Ωψ,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.

Highlights

Astronomical observations brought important changes in modern cosmology [1]
The Letter discusses observational constraint on “energy contributions” arising in certain cosmological models based on metric-affine gravity (MAG)
In particular it is focused on the non-standard term a−6. We test this model against the SNIa data, the location of the peaks of the cosmic microwave background (CMB) power spectrum, and constraints from the big-bang nucleosynthesis (BBN)

Summary

Introduction

While the type Ia supernovae (SNIa) data are most often employed, the cosmic microwave background (CMB) observations and big-bang nucleosynthesis (BBN) analysis can be used They allow the exotic physics of cosmological models to be checked against the observational data [2]. Where H = d ln a/dt is the Hubble function, t is the cosmological time, a = a(t) is the scale factor, Ωm,0, ΩΛ,0 and Ωψ,0 are the density parameters for dust matter, the cosmological constant and fictitious fluid which mimics “non-Riemannian effects”, respectively. Their values in the present epoch are marked by the index “0”. The sign of the parameter υ is undetermined and it can assume both positive and negative values

Constraint from the SNIa

CMB peaks in the MAG model

Constraint from the BBN

Conclusion