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A general framework to test gravity using galaxy clusters I : modelling the dynamical mass of haloes in f(R) gravity.

Mitchell, Myles A and He, Jian-hua and Arnold, Christian and Li, Baojiu (2018) 'A general framework to test gravity using galaxy clusters I : modelling the dynamical mass of haloes in f(R) gravity.', Monthly notices of the Royal Astronomical Society., 477 (1). pp. 1133-1152.


We propose a new framework for testing gravity using cluster observations, which aims to provide an unbiased constraint on modified gravity models from Sunyaev Zel’dovich (SZ) and X-ray cluster counts and the cluster gas fraction, among other possible observables. Focusing on a popular f(R) model of gravity, we propose a novel procedure to recalibrate mass scaling relations from ΛCDM to f(R) gravity for SZ and X-ray cluster observables. We find that the complicated modified gravity effects can be simply modelled as a dependence on a combination of the background scalar field and redshift, fR(z)/(1 + z), regardless of the f(R) model parameter. By employing a large suite of N-body simulations, we demonstrate that a theoretically derived tanh  fitting formula is in excellent agreement with the dynamical mass enhancement of dark matter haloes for a large range of background field parameters and redshifts. Our framework is sufficiently flexible to allow for tests of other models and inclusion of further observables, and the one-parameter description of the dynamical mass enhancement can have important implications on the theoretical modelling of observables and on practical tests of gravity.

Item Type:Article
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Publisher statement:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2018 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:07 March 2018
Date deposited:03 April 2018
Date of first online publication:09 March 2018
Date first made open access:24 April 2018

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