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Confronting the IR Fixed Point Cosmology with High Redshift Observations

We use high-redshift type Ia supernova and compact radio source data in order to test the infrared (IR) fixed point model of the late Universe which was proposed recently. It describes a cosmology with a time dependent cosmological constant and Newton constant whose dynamics arises from an underlying renormalization group flow near an IR-attractive fixed point. Without any finetuning or quintessence field it yields $\Omega_{\rm M}=\Omega_{\Lambda}=1/2$. Its characteristic $t^{4/3}$- dependence of the scale factor leads to a distance-redshift relation whose predictions are compared both to the supernova and to the radio source data. According to the $\chi^2$ test, the fixed point model reproduces the data at least as well as the best-fit (Friedmann-Robertson-Walker) standard cosmology (see Fig.(1.23). Using median statistics and a Bayesian model selection criterion we show that the fixed point cosmology has even better chances of being the correct theory of the late Universe than any standard cosmology. Furthermore, we extend the original fixed point model by assuming that the fixed point epoch is preceded by an era with constant $G$ and $\Lambda$. By means of a Monte Carlo simulation we show that the data expected from the forthcoming SNAP satellite mission could detect the transition to the fixed point regime provided it took place at a redshift of less than about $0.5$ ().


next up previous contents index
Next: Arnowittr-Deser-Misner gravity with variable Up: Theoretical Cosmology Previous: Cosmological Perturbations in Renormalization   Contents   Index
Innocenza Busa' 2005-11-14