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Exploring the liminality : properties of haloes and subhaloes in borderline f(R) gravity.

Shi, D. and Li, B. and Han, J. and Gao, L. and Hellwing, W. A. (2015) 'Exploring the liminality : properties of haloes and subhaloes in borderline f(R) gravity.', Monthly notices of the Royal Astronomical Society., 452 (3). pp. 3179-3191.

Abstract

We investigate the properties of dark matter haloes and subhaloes in an f(R) gravity model with |fR0| = 10−6, using a very-high-resolution N-body simulation. The model is a borderline between being cosmologically interesting and yet still consistent with current data. We find that the halo mass function in this model has a maximum 20 per cent enhancement compared with the Λ-cold-dark-matter (ΛCDM) predictions between z = 1 and 0. Because of the chameleon mechanism which screens the deviation from standard gravity in dense environments, haloes more massive than 1013 h−1 M⊙ in this f(R) model have very similar properties to haloes of similar mass in ΛCDM, while less massive haloes, such as that of the Milky Way, can have steeper inner density profiles and higher velocity dispersions due to their weaker screening. The halo concentration is remarkably enhanced for low-mass haloes in this model due to a deepening of the total gravitational potential. Contrary to the naive expectation, the halo formation time zf is later for low-mass haloes in this model, a consequence of these haloes growing faster than their counterparts in ΛCDM at late times and the definition of zf. Subhaloes, especially those less massive than 1011 h−1 M⊙, are substantially more abundant in this f(R) model for host haloes less massive than 1013 h−1 M⊙. We discuss the implications of these results for the Milky Way satellite abundance problem. Although the overall halo and subhalo properties in this borderline f(R) model are close to their ΛCDM predictions, our results suggest that studies of the Local Group and astrophysical systems, aided by high-resolution simulations, can be valuable for further tests of it.

Item Type:Article
Keywords:Gravitation, Methods: numerical, Galaxies: haloes, Cosmology: theory, Dark matter, Large-scale structure of Universe.
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Status:Peer-reviewed
Publisher Web site:http://dx.doi.org/10.1093/mnras/stv1549
Publisher statement:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Date accepted:09 July 2015
Date deposited:04 September 2015
Date of first online publication:September 2015
Date first made open access:No date available

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