Model independent analysis of dark energy I: Supernova fitting result

Abstract

The nature of dark energy is a mystery to us. This paper uses the supernova data to explore the property of dark energy by some model independent methods. We first Talyor expanded the scale factor $a(t)$ to find out the deceleration parameter $q_0<0$. This result just invokes the Robertson-Walker metric. Then we discuss several different parameterizations used in the literature. We find that ${\Omega }_{DE0}$ is almost less than -1 at $1\sigma$ level. We also find that the transition redshift from deceleration phase to acceleration phase is $z_{\mathrm{T}}\sim 0.3$.

Comments: v4: minor corrections, main results unchanged. 10 figures, use revtex, 7 pages, v5: refences updated, will appear in Class. Quantum Grav