Confirmation of general relativity on large scales from weak lensing and galaxy velocities

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, EG, that combines measures of large-scale gravitational lensing, galaxy clustering and structure growth...

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Bibliographic Details
Published in:Nature (London) 2010-03, Vol.464 (7286), p.256-258
Main Authors: Baldauf, Tobias, Smith, Robert E, Lombriser, Lucas, Seljak, Uros, Reyes, Reinabelle, Mandelbaum, Rachel, Gunn, James E
Format: Article
Language:English
Subjects:
639/33/34/124
639/33/34/863
Astronomy
Clustering
Cosmology
Galaxies
Gravitation
Gravity
Humanities and Social Sciences
letter
Mathematical models
multidisciplinary
Observations
Perturbation methods
Relativity
Science
Science (multidisciplinary)
Speed
Stars & galaxies
Uncertainty
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Summary: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, EG, that combines measures of large-scale 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 EG 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 non-zero, which leads to changes in the growth of structure and the strength of the gravitational lensing effect. Here we report that EG = 0.39 ± 0.06 on length scales of tens of megaparsecs, in agreement with the general relativistic prediction of EG   0.4. The measured value excludes a model within the tensor–vector–scalar 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.
ISSN:0028-0836
1476-4687
DOI:10.1038/nature08857