Publication Date:
2015-07-16
Description:
The chameleon gravity model postulates the existence of a scalar field that couples with matter to mediate a fifth force. If it exists, this fifth force would influence the hot X-ray emitting gas filling the potential wells of galaxy clusters. However, it would not influence the clusters weak lensing signal. Therefore, by comparing X-ray and weak lensing profiles, one can place upper limits on the strength of a fifth force. This technique has been attempted before using a single, nearby cluster (Coma, z = 0.02). Here we apply the technique to the stacked profiles of 58 clusters at higher redshifts (0.1 〈 z 〈 1.2), including 12 new to the literature, using X-ray data from the XMM Cluster Survey and weak lensing data from the Canada–France–Hawaii–Telescope Lensing Survey. Using a multiparameter Markov chain Monte Carlo analysis, we constrain the two chameleon gravity parameters (β and ). Our fits are consistent with general relativity, not requiring a fifth force. In the special case of f ( R ) gravity (where $\beta = \sqrt{1/6}$ ), we set an upper limit on the background field amplitude today of | f R0 | 〈 6 x 10 –5 (95 per cent CL). This is one of the strongest constraints to date on | f R0 | on cosmological scales. We hope to improve this constraint in future by extending the study to hundreds of clusters using data from the Dark Energy Survey.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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