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Galaxy infall kinematics as a test of modified gravity

Zu, Y.; Weinberg, D.H.; Jennings, E.; Li, B.; Wyman, M.

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Authors

Y. Zu

D.H. Weinberg

E. Jennings

M. Wyman



Abstract

Infrared modifications of General Relativity (GR) can be revealed by comparing the mass of galaxy clusters estimated from weak lensing to that from infall kinematics. We measure the 2D galaxy velocity distribution in the cluster infall region by applying the galaxy infall kinematics (GIK) model developed by Zu and Weinberg (2013) to two suites of f(R) and Galileon modified gravity simulations. Despite having distinct screening mechanisms, namely, the Chameleon and the Vainshtein effects, the f(R) and Galileon clusters exhibit very similar deviations in their GIK profiles from GR, with ~ 100-200 k/s enhancement in the characteristic infall velocity at r=5 Mpc/h and 50-100 km/s broadening in the radial and tangential velocity dispersions across the entire infall region, for clusters with mass ~ 10^{14} Msol/h at z=0.25. These deviations are detectable via the GIK reconstruction of the redshift--space cluster-galaxy cross-correlation function, xi_cg^s(r_p,r_\pi), which shows ~ 1-2 Mpc/h increase in the characteristic line-of-sight distance r_\pi^c at r_p<6 Mpc/h from GR predictions. With overlapping deep imaging and large redshift surveys in the future, we expect that the GIK modelling of xi_cg^s, in combination with the stacked weak lensing measurements, will provide powerful diagnostics of modified gravity theories and the origin of cosmic acceleration.

Journal Article Type Article
Publication Date Dec 1, 2014
Deposit Date Nov 7, 2013
Publicly Available Date May 21, 2014
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 445
Issue 2
Pages 1885-1897
DOI https://doi.org/10.1093/mnras/stu1739
Public URL https://durham-repository.worktribe.com/output/1444782
Related Public URLs http://arxiv.org/abs/1310.6768

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2014 The Authors
Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.







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