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The connection between halo concentrations and assembly histories : a probe of gravity?

Oleśkiewicz, Piotr and Baugh, Carlton M. and Ludlow, Aaron (2019) 'The connection between halo concentrations and assembly histories : a probe of gravity?', Monthly notices of the Royal Astronomical Society., 489 (4). pp. 4658-4668.


We use two high resolution N-body simulations, one assuming general relativity and the other the Hu-Sawicki form of f(R) gravity with |f¯R|=10−6⁠, to investigate the concentration–formation time relation of dark matter haloes. We assign haloes to logarithmically spaced mass bins, and fit median density profiles and extract median formation times in each bin. At fixed mass, haloes in modified gravity are more concentrated than those in GR, especially at low masses and at low redshift, and do not follow the concentration–formation time relation seen in GR. We assess the sensitivity of the relation to how concentration and formation time are defined, as well as to the segregation of the halo population by the amount of gravitational screening. We find a clear difference between halo concentrations and assembly histories displayed in modified gravity and those in GR. Existing models for the mass–concentration–redshift relation that have gained success in cold and warm dark matter models require revision in f(R) gravity.

Item Type:Article
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Publisher statement:This article has been accepted for publication in the Monthly notices of the Royal Astronomical Society ©: 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:21 August 2019
Date deposited:17 September 2019
Date of first online publication:07 September 2019
Date first made open access:No date available

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