Cosmological Tests of Gravity with the Latest Observations

We perform observational tests of modified gravity on cosmological scales following model-dependent and model-independent approaches using the latest astronomical observations, including measurements of the local Hubble constant, cosmic microwave background, the baryonic acoustic oscillations and redshift space distortions derived from galaxy surveys including the Sloan Digital Sky Survey BOSS and eBOSS, as well as the weak lensing observations performed by the CFHTLenS team. Combining all these data sets, we find a deviation from the prediction of general relativity in both the effective Newton's constant, mu(a, k), and in the gravitational slip, eta(a, k). The deviation is at a 3.1 sigma level in the joint {mu(a, k), eta(a, k)} space using a two-parameter phenomenological model for mu and eta, and reaches a 3.7 sigma level if a general parameterization is used. This signal, which may be subject to unknown observational systematics, or a sign of new physics, is worth further investigating with forthcoming observations.