English

Testing and selection of cosmological models with $(1+z)^6$ corrections

General Relativity and Quantum Cosmology 2008-11-26 v3

Abstract

In the paper we check whether the contribution of ()(1+z)6(-)(1+z)^6 type in the Friedmann equation can be tested. We consider some astronomical tests to constrain the density parameters in such models. We describe different interpretations of such an additional term: geometric effects of Loop Quantum Cosmology, effects of braneworld cosmological models, non-standard cosmological models in metric-affine gravity, and models with spinning fluid. Kinematical (or geometrical) tests based on null geodesics are insufficient to separate individual matter components when they behave like perfect fluid and scale in the same way. Still, it is possible to measure their overall effect. We use recent measurements of the coordinate distances from the Fanaroff-Riley type IIb (FRIIb) radio galaxy (RG) data, supernovae type Ia (SNIa) data, baryon oscillation peak and cosmic microwave background radiation (CMBR) observations to obtain stronger bounds for the contribution of the type considered. We demonstrate that, while ρ2\rho^2 corrections are very small, they can be tested by astronomical observations -- at least in principle. Bayesian criteria of model selection (the Bayesian factor, AIC, and BIC) are used to check if additional parameters are detectable in the present epoch. As it turns out, the Λ\LambdaCDM model is favoured over the bouncing model driven by loop quantum effects. Or, in other words, the bounds obtained from cosmography are very weak, and from the point of view of the present data this model is indistinguishable from the Λ\LambdaCDM one.

Keywords

Cite

@article{arxiv.0706.0283,
  title  = {Testing and selection of cosmological models with $(1+z)^6$ corrections},
  author = {Marek Szydlowski and Wlodzimierz Godlowski and Tomasz Stachowiak},
  journal= {arXiv preprint arXiv:0706.0283},
  year   = {2008}
}

Comments

19 pages, 1 figure. Version 2 generally revised and accepted for publication