Testing Einstein Gravity with Cosmic Growth and Expansion
  We test Einstein gravity using cosmological observations of both expansion
and structure growth, including the latest data from supernovae (Union2.1), CMB
(WMAP7), weak lensing (CFHTLS) and peculiar velocity of galaxies (WiggleZ). We
fit modified gravity parameters of the generalized Poisson equations
simultaneously with the effective equation of state for the background
evolution, exploring the covariances and model dependence. The results show
that general relativity is a good fit to the combined data. Using a Pad{\'e}
approximant form for the gravity deviations accurately captures the time and
scale dependence for theories like $f(R)$ and DGP gravity, and weights high and
low redshift probes fairly. For current observations, cosmic growth and
expansion can be fit simultaneously with little degradation in accuracy, while
removing the possibility of bias from holding one aspect fixed.
