Probing Dark Energy Dynamics from Current and Future Cosmological Observations

TL;DR

This paper constrains the dark energy equation-of-state w(z) using current cosmological data, finds mild hints of dynamics crossing -1, and forecasts future survey improvements in precision.

Contribution

It provides the first combined analysis of current data with localized principal component analysis and forecasts future constraints from upcoming surveys.

Findings

Current data is consistent with LCDM but hints at w(z) crossing -1.

Future surveys can improve precision of w(z) measurements by a factor of 10.

A model with w(z) crossing -1 is mildly favored at 95% confidence.

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 SDSS data. Based on the localized principal component analysis and the model selection criteria, we find that the LCDM model is generally consistent with the current data, yet there exists weak hint of the possible dynamics of dark energy. In particular, a model predicting w(z)<-1 at z\in[0.25,0.5) and w(z)>-1 at z\in[0.5,0.75), which means that w(z) crosses -1 in the range of z\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 JDEM, Planck and LSST, 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.