Exploring the Latest Union2 SNIa Dataset by Using Model-Independent Parametrization Methods

Abstract

We explore the cosmological consequences of the recently released Union2 sample of 557 Type Ia supernovae (SNIa). Combining this latest SNIa dataset with the Cosmic microwave background (CMB) anisotropy data from the Wilkinson Microwave Anisotropy Probe 7 year (WMAP7) observations and the baryon acoustic oscillation (BAO) results from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7), we measure the dark energy density function $f(z)\equiv {\rho }_{de}(z)/{\rho }_{de}(0)$ as a free function of redshift. Two model-independent parametrization methods (the binned parametrization and the polynomial interpolation parametrization) are used in this paper. By using the ${\chi }^2$ statistic and the Bayesian information criterion, we find that the current observational data are still too limited to distinguish which parametrization method is better, and a simple model has advantage in fitting observational data than a complicated model. Moreover, it is found that all these parametrizations demonstrate that the Union2 dataset is still consistent with a cosmological constant at 1$\sigma$ confidence level. Therefore, the Union2 dataset is different from the Constitution SNIa dataset, which more favors a dynamical dark energy.

11 pages, 8 figures, 2 tables, accepted for publication in PRD

References in corpus (14)

• Dynamics of dark energy
• Improved Cosmological Constraints from New, Old and Combined Supernova Datasets
• Improved Dark Energy Constraints from ~100 New CfA Supernova Type Ia Light Curves
• A Dark Energy Model Characterized by the Age of the Universe
• A New Model of Agegraphic Dark Energy
• Holographic dark energy models: A comparison from the latest observational data
• Alleviation of Cosmic Age Problem In Interacting Dark Energy Model
• 2-loop Quantum Yang-Mills Condensate as Dark Energy
• Fitting the Constitution SNIa Data with Redshift Binned Parameterization Method
• Yang-Mills condensate dark energy coupled with matter and radiation
• 3-loop Yang-Mills Condensate Dark Energy Model And Its Cosmological Constraints
• Narrowing Constraints with Type Ia Supernovae: Converging on a Cosmological Constant
• Constraining the evolution of dark energy with type Ia supernovae and gamma-ray bursts
• Gamma-ray burst contributions to constraining the evolution of dark energy

Cited by in corpus (1)

• Probing Cosmic Acceleration by Using the SNLS3 SNIa Dataset