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Nonlinear structure formation in Nonlocal Gravity

Barreira, A.; Li, B.; Hellwing, W.A.; Baugh, C.; Pascoli, S.

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A. Barreira

W.A. Hellwing


We study the nonlinear growth of structure in nonlocal gravity models with the aid of N-body simulation and the spherical collapse and halo models. We focus on a model in which the inverse-squared of the d'Alembertian operator acts on the Ricci scalar in the action. For fixed cosmological parameters, this model differs from ΛCDM by having a lower late-time expansion rate and an enhanced and time-dependent gravitational strength ~ 6% larger today). Compared to ΛCDM today, in the nonlocal model, massive haloes are slightly more abundant (by ~ 10% at M ~ 1014 M⊙/h) and concentrated ≈ 8% enhancement over a range of mass scales), but their linear bias remains almost unchanged. We find that the Sheth-Tormen formalism describes the mass function and halo bias very well, with little need for recalibration of free parameters. The fitting of the halo concentrations is however essential to ensure the good performance of the halo model on small scales. For k gsim 1 h/Mpc, the amplitude of the nonlinear matter and velocity divergence power spectra exhibits a modest enhancement of ~ 12% to 15%, compared to ΛCDM today. This suggests that this model might only be distinguishable from ΛCDM by future observational missions. We point out that the absence of a screening mechanism may lead to tensions with Solar System tests due to local time variations of the gravitational strength, although this is subject to assumptions about the local time evolution of background averaged quantities.

Journal Article Type Article
Acceptance Date Aug 20, 2014
Online Publication Date Sep 14, 2014
Publication Date Sep 14, 2014
Deposit Date Oct 2, 2014
Publicly Available Date Aug 26, 2016
Journal Journal of Cosmology and Astroparticle Physics
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 2014
Issue 09
Article Number 031
Public URL
Related Public URLs


Accepted Journal Article (1.5 Mb)

Copyright Statement
This is an author-created, un-copyedited version of an article published in Journal of Cosmology and Astroparticle Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at

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