Spherical collapse and the halo model in braneworld gravity

Schmidt, Fabian; Hu, Wayne; Lima, M.

doi:10.1103/physrevd.81.063005

Cited by 109 publications

(160 citation statements)

References 59 publications

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“…Figure 21 shows the fractional deviations in the mass function for f (R) and DGP models [395,397,1000,1001]. For f (R) models significant departures from GR may occur if the scales involved in forming clusters are smaller than the Compton wavelength of the scalar f R but larger than the scale of chameleon effects that screen halos from the modified forces and drive the theory to GR.…”

Section: Halo Abundances and Profilesmentioning

confidence: 99%

“…Two essential products from simulations are the nonlinear mass power spectrum and the mass function of galaxy and cluster sized halos [395,397,398,[1000][1001][1002][1003]. For specific models these predictions allow for comparisons to data.…”

Section: Halo Abundances and Profilesmentioning

confidence: 99%

“…For MG theories, the simulations incorporate the coupling of the density field to a scalar field such as f R for f (R) models. A number of papers have reported simulations that include such a coupling for both f (R) and DGP gravity [395,[395][396][397][398][1000][1001][1002].…”

Section: Halo Abundances and Profilesmentioning

confidence: 99%

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Beyond the cosmological standard model

et al. 2015

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After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests.We begin by reviewing recent attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must "screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second derivatives of the field are important. Examples of the first class, such as f (R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories and discuss prospects for completion in a more fundamental theory. We describe experimental tests of each class of theories, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. Finally, we discuss prospects for future tests which will be sensitive to different signatures of new physics in the gravitational sector.The review is structured so that those parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

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Section: Halo Abundances and Profilesmentioning

confidence: 99%

Section: Halo Abundances and Profilesmentioning

confidence: 99%

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Beyond the cosmological standard model

et al. 2015

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“…In order to understand how the Vainshtein mechanism operates, it is useful to consider spherically symmetric solutions [35,36]. For a spherically symmetric object, the scalar field equation (4) reduces to…”

Section: B Spherically Symmetric Solutionmentioning

confidence: 99%

The Vainshtein mechanism in the cosmic web

Falck

Koyama

Zhao

et al. 2014

J. Cosmol. Astropart. Phys.

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We investigate the dependence of the Vainshtein screening mechanism on the cosmic web morphology of both dark matter particles and halos as determined by ORIGAMI. Unlike chameleon and symmetron screening, which come into effect in regions of high density, Vainshtein screening instead depends on the dimensionality of the system, and screened bodies can still feel external fields. ORIGAMI is well-suited to this problem because it defines morphologies according to the dimensionality of the collapsing structure and does not depend on a smoothing scale or density threshold parameter. We find that halo particles are screened while filament, wall, and void particles are unscreened, and this is independent of the particle density. However, after separating halos according to their large scale cosmic web environment, we find no difference in the screening properties of halos in filaments versus halos in clusters. We find that the fifth force enhancement of dark matter particles in halos is greatest well outside the virial radius. We confirm the theoretical expectation that even if the internal field is suppressed by the Vainshtein mechanism, the object still feels the fifth force generated by the external fields, by measuring peculiar velocities and velocity dispersions of halos. Finally, we investigate the morphology and gravity model dependence of halo spins, concentrations, and shapes.

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“…Recently the growth of dark matter perturbations in the normal branch of the DGP model (plus sign in Eq. 1.21), together with a cosmological constant, has been studied in N-body simulations (Schmidt et al, 2010).…”

Section: Cosmological Modelsmentioning

confidence: 99%

Simulations of Dark Energy Cosmologies

Jennings

2012

Springer Theses

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source• a link is made to the metadata record in Durham E-Theses• the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. No part of this thesis has been submitted elsewhere for any other degree or qualification.The work of others has been duly acknowledged.The copyright of this thesis rests with the author. No quotations from it should be published without the author's prior written consent and information derived from it should be acknowledged. AbstractFuture galaxy redshift surveys will make high precision measurements of the cosmic expansion history and the growth of structure which will potentially allow us to distinguish between different scenarios for the accelerating expansion of the Universe. In this thesis we study the nonlinear growth of cosmic structure in different dark energy models, using ultra-large volume N-body simulations. We measure key observables such as the growth of large scale structure, the halo mass function and baryonic acoustic oscillations.We study the power spectrum in redshift space in ΛCDM and quintessence dark energy models and test predictions for the form of the redshift space distortions. An improved model for the redshift space power spectrum, including the non-linear velocity divergence power spectrum, is presented. We have found a density-velocity relation which is cosmology independent and which relates the non-linear velocity divergence spectrum to the non-linear matter power spectrum. We provide a formula which generates the non-linear velocity divergence P(k) at any redshift, using only the non-linear matter power spectrum and the linear growth factor at the desired redshift. We also demonstrate for the first time that competing cosmological models with identical expansion histories -one with a scalar field and the other with a time-dependent change to Newton's gravitational constant -can indeed be distinguished by a measurement of the rate at which structures grow.Our calculations show that linear theory models for the power spectrum in redshift space fail to recover the correct growth rate on surprisingly large scales, leading to catastrophic systematic errors. Improved theoretical models, which have been calibrated against simulations, are needed to exploit the exquisitely accurate clustering measurements expected from future surveys.

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Spherical collapse and the halo model in braneworld gravity

Cited by 109 publications

References 59 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

The Vainshtein mechanism in the cosmic web

Simulations of Dark Energy Cosmologies

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