Probing dark energy dynamics from current and future cosmological observations

Abstract

We report the constraints on the dark energy equation-of-state $w(z)$ using the latest ``Constitution'' SNe sample combined with the WMAP5 and Sloan Digital Sky Survey data. Assuming a flat Universe, and utilizing the localized principal component analysis and the model selection criteria, we find that the $\ensuremath{\Lambda}\mathrm{CDM}$ model is generally consistent with the current data, yet there exists a weak hint of the possible dynamics of dark energy. In particular, a model predicting $w(z)<\ensuremath{-}1$ at $z\ensuremath{\in}[0.25,0.5)$ and $w(z)>\ensuremath{-}1$ at $z\ensuremath{\in}[0.5,0.75)$, which means that $w(z)$ crosses $\ensuremath{-}1$ in the range of $z\ensuremath{\in}[0.25,0.75)$, is mildly favored at 95% confidence level. Given the best fit model for current data as a fiducial model, we make future forecast from the joint data sets of Joint Dark Energy Mission, Planck, and Large Synoptic Survey Telescope, and we find that the future surveys can reduce the error bars on the $w$ bins by roughly a factor of 10 for a 5-$w$-bin model.