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Title: Nonlocal gravity and structure in the Universe

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Sponsoring Org.:
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Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 90; Journal Issue: 4; Journal ID: ISSN 1550-7998
American Physical Society
Country of Publication:
United States

Citation Formats

Dodelson, Scott, and Park, Sohyun. Nonlocal gravity and structure in the Universe. United States: N. p., 2014. Web. doi:10.1103/PhysRevD.90.043535.
Dodelson, Scott, & Park, Sohyun. Nonlocal gravity and structure in the Universe. United States. doi:10.1103/PhysRevD.90.043535.
Dodelson, Scott, and Park, Sohyun. Tue . "Nonlocal gravity and structure in the Universe". United States. doi:10.1103/PhysRevD.90.043535.
title = {Nonlocal gravity and structure in the Universe},
author = {Dodelson, Scott and Park, Sohyun},
abstractNote = {},
doi = {10.1103/PhysRevD.90.043535},
journal = {Physical Review D},
number = 4,
volume = 90,
place = {United States},
year = {Tue Aug 26 00:00:00 EDT 2014},
month = {Tue Aug 26 00:00:00 EDT 2014}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevD.90.043535

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Cited by: 20works
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  • The observed acceleration of the Universe can be explained by modifying general relativity. One such attempt is the nonlocal model of Deser and Woodard. Here we fix the background cosmology using results from the Planck satellite and examine the predictions of nonlocal gravity for the evolution of structure in the universe, confronting the model with three tests: gravitational lensing, redshift space distortions, and the estimator of gravitymore » $$E_G$$. Current data favor general relativity (GR) over nonlocal gravity: fixing primordial cosmology with the best fit parameters from Planck leads to weak lensing results favoring GR by 5.9 sigma; redshift space distortions measurements of the growth rate preferring GR by 7.8 sigma; and the single measurement of $$E_G$$ favoring GR, but by less than 1-sigma. The significance holds up even after the parameters are allowed to vary within Planck limits. The larger lesson is that a successful modified gravity model will likely have to suppress the growth of structure compared to general relativity.« less
  • 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 ∼ 10{sup 14} M{sub ⊙}/h) and concentrated ≈ 8% enhancement over a range of massmore » 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 ∼> 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.« less
  • It has been argued that a Universe governed by Eddington-Born-Infeld gravity can be compatible with current cosmological constraints. The extra fields introduced in this theory can behave as both dark matter and dark energy, unifying the dark sector in one coherent framework. We show the various roles the extra fields can play in the expansion of the Universe and study the evolution of linear perturbations in the various regimes. We find that, as a unified theory of the dark sector, Eddington-Born-Infeld gravity will lead to excessive fluctuations in the cosmic microwave background on large scales. In the presence of amore » cosmological constant, however, the extra fields can behave as a form of nonparticulate dark matter and can lead to a cosmology which is entirely compatible with current observations of large scale structure. We discuss the interpretation of this form of dark matter and how it can differ from standard, particulate dark matter.« less
  • Future galaxy surveys hope to distinguish between the dark energy and modified gravity scenarios for the accelerating expansion of the universe using the distortion of clustering in redshift space. The aim is to model the form and size of the distortion to infer the rate at which large-scale structure grows. We test this hypothesis and assess the performance of current theoretical models for the redshift space distortion using large volume N-body simulations of the gravitational instability process. We simulate competing cosmological models which have identical expansion histories-one is a quintessence dark energy model with a scalar field and the othermore » is a modified gravity model with a time-varying gravitational constant-and demonstrate that they do indeed produce different redshift space distortions. This is the first time that this approach has been verified using a technique that can follow the growth of structure at the required level of accuracy. Our comparisons show that theoretical models for the redshift space distortion based on linear perturbation theory give a surprisingly poor description of the simulation results. Furthermore, the application of such models can give rise to catastrophic systematic errors leading to incorrect interpretation of the observations. We show that an improved model is able to extract the correct growth rate. Further enhancements to theoretical models of redshift space distortions, calibrated against simulations, are needed to fully exploit the forthcoming high-precision clustering measurements.« less
  • We study inflationary cosmology and the late-time accelerated expansion of the universe in nonminimal Yang-Mills (YM) theory, in which the YM field couples to a function of the scalar curvature. It is shown that power-law inflation can be realized due to the nonminimal YM field-gravitational coupling which may be caused by quantum corrections. Moreover, it is demonstrated that both inflation and the late-time accelerated expansion of the universe can be realized in a modified YM-F(R) gravity which is consistent with solar-system tests. Furthermore, it is shown that this result can be realized also in a nonminimal vector-F(R) gravity. In addition,more » we consider the duality of the nonminimal electromagnetic theory and that of the nonminimal YM theory, and also discuss the cosmological reconstruction of the YM theory.« less