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The Effect of Modified Gravity on the Odds of the Bound Violations of the Turn-around Radii

Lee, Jounghun; Li, Baojiu

The Effect of Modified Gravity on the Odds of the Bound Violations of the Turn-around Radii Thumbnail


Authors

Jounghun Lee



Abstract

The turn-around radii of the galaxy groups show the imprint of a long battle between their self-gravitational forces and the accelerating space. The standard ΛCDM cosmology based on the general relativity (GR) predicts the existence of an upper bound on the expectation value of the turn-around radius that is rarely violated by individual galaxy groups. We speculate that a deviation of the gravitational law from GR on the cosmological scale could cause an appreciable shift of the mean turn-around radius to higher values and make the occurrence of the bound violation more probable. Analyzing the data from high-resolution N-body simulations for two specific models with modified gravity (MG) and the standard GR+ΛCDM cosmology, we determine the turn-around radii of the massive Rockstar groups from the peculiar motions of the galactic halos located in the bound zone where the fifth force generated by MG is expected to be, at most, partially shielded. We detect a $4\sigma $ signal of difference in the odds of the bound violations between a fiducial MG and the GR models, which proves that the odds of the bound violations increase with the strength of the fifth force produced by the presence of MG. The advantage of using the odds of the bound violations as a complementary diagnostics to probe the nature of gravity is discussed.

Journal Article Type Article
Acceptance Date Apr 27, 2017
Online Publication Date Jun 6, 2017
Publication Date Jun 6, 2017
Deposit Date Jul 5, 2017
Publicly Available Date Jul 5, 2017
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 842
Issue 1
Article Number 2
DOI https://doi.org/10.3847/1538-4357/aa706f
Public URL https://durham-repository.worktribe.com/output/1356104

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© 2017. The American Astronomical Society. All rights reserved.






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