Confirmation of general relativity on large scales from weak lensing and galaxy velocities
Abstract
Although general relativity underlies modern cosmology, its applicability on cosmological length scales has yet to be stringently tested. Such a test has recently been proposed, using a quantity, E_{G}, that combines measures of largescale gravitational lensing, galaxy clustering and structure growth rate. The combination is insensitive to `galaxy bias' (the difference between the clustering of visible galaxies and invisible dark matter) and is thus robust to the uncertainty in this parameter. Modified theories of gravity generally predict values of E_{G} different from the general relativistic prediction because, in these theories, the `gravitational slip' (the difference between the two potentials that describe perturbations in the gravitational metric) is nonzero, which leads to changes in the growth of structure and the strength of the gravitational lensing effect. Here we report that E_{G} = 0.39+/0.06 on length scales of tens of megaparsecs, in agreement with the general relativistic prediction of E_{G}~0.4. The measured value excludes a model within the tensorvectorscalar gravity theory, which modifies both Newtonian and Einstein gravity. However, the relatively large uncertainty still permits models within f() theory, which is an extension of general relativity. A fivefold decrease in uncertainty is needed to rule out these models.
 Publication:

Nature
 Pub Date:
 March 2010
 DOI:
 10.1038/nature08857
 arXiv:
 arXiv:1003.2185
 Bibcode:
 2010Natur.464..256R
 Keywords:

 Astrophysics  Cosmology and Extragalactic Astrophysics;
 General Relativity and Quantum Cosmology
 EPrint:
 Submitted version