Is dark energy evolving?
  We look for evidence for the evolution in dark energy density by employing
Principal Component Analysis (PCA). Distance redshift data from supernovae and
baryon acoustic oscillations (BAO) along with WMAP7 distance priors are used to
put constraints on curvature parameter Omega_k and dark energy parameters. The
data sets are consistent with a flat Universe. The constraints on the dark
energy evolution parameters obtained from supernovae (including CMB distance
priors) are consistent with a flat Lambda-CDM Universe. On the other hand, in
the parameter estimates obtained from the addition of BAO data the second
principal component, which characterize a non-constant contribution from dark
energy, is non-zero at 1-sigma. This could be a systematic effect and future
BAO data holds key to making more robust claims.
