Model-independent analysis of dark energy: supernova fitting result

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 q₀<0. This result just invokes the Robertson-Walker metric. Then we discuss several different parameterizations used in the literature. We find that ΩDE0 is almost less than -1 at 1σ level. We also find that the transition redshift from deceleration phase to acceleration phase is zT~ 0.3.