No evidence for dark energy dynamics from a global analysis of cosmological data

We use a variant of principal component analysis to investigate the possible temporal evolution of the dark energy equation of state, $w(z)$. We constrain $w(z)$ in multiple redshift bins, utilizing the most recent data from type Ia supernovae, the cosmic microwave background, baryon acoustic oscillations, the integrated Sachs-Wolfe effect, galaxy clustering, and weak lensing data. Unlike other recent analyses, we find no significant evidence for evolving dark energy; the data remain completely consistent with a cosmological constant. We also study the extent to which the time evolution of the equation of state would be constrained by a combination of current- and future-generation surveys, such as Planck and the Joint Dark Energy Mission.

Figure 1

The upper panel shows uncorrelated constraints on the dark energy EOS parameters using both $\mathrm{WMAP}+\mathrm{UNION}+\mathrm{BAO}$ and $\mathrm{WMAP}+\mathrm{\text{Constitution}}+\mathrm{BAO}$; the points for the Constitution data set have been slightly shifted to facilitate comparison between the two cases: we find no significant difference between UNION and Constitution. The dark (blue) line is the reconstructed $w(z)$ using a cubic spline interpolation between the nodes and it is related to $\mathrm{WMAP}+\mathrm{UNION}+\mathrm{BAO}$; the lower panel shows results from a “global” data set given by $\mathrm{WMAP}+\mathrm{UNION}+\mathrm{BAO}+\mathrm{WL}+\mathrm{ISW}+\mathrm{LSS}$; error bars are always at $2\sigma$.

Figure 2

Uncorrelated constraints on the dark energy equation of state parameters, for mock data sets from Planck and JDEM; error bars are at $2\sigma$.