First-Year Sloan Digital Sky Survey-II (SDSS-II) Supernova Results: Constraints on Non-Standard Cosmological Models

TL;DR

This study uses SDSS-II supernova data combined with other cosmological observations to evaluate and rank various standard and non-standard cosmological models, finding that model performance depends on the analysis method used.

Contribution

It provides a comparative analysis of multiple cosmological models using combined datasets and different light-curve fitting methods, highlighting the impact of analysis choices on model ranking.

Findings

Exotic models fit the data better with MLCS2k2 fitter.

Standard Lambda-CDM is favored with SALT-II fitter.

Inhomogeneous LTB models require extra parameters not supported by data.

Abstract

We use the new SNe Ia discovered by the SDSS-II Supernova Survey together with additional supernova datasets as well as observations of the cosmic microwave background and baryon acoustic oscillations to constrain cosmological models. This complements the analysis presented by Kessler et al. in that we discuss and rank a number of the most popular non-standard cosmology scenarios. When this combined data-set is analyzed using the MLCS2k2 light-curve fitter, we find that more exotic models for cosmic acceleration provide a better fit to the data than the Lambda-CDM model. For example, the flat DGP model is ranked higher by our information criteria tests than the standard model. When the dataset is instead analyzed using the SALT-II light-curve fitter, the standard cosmological constant model fares best. Our investigation also includes inhomogeneous Lemaitre-Tolman-Bondi (LTB) models. While our LTB models can be made to fit the supernova data as well as any other model, the extra parameters they require are not supported by our information criteria analysis.