Dynamical masses in modified gravity

Schmidt, Fabian

doi:10.1103/physrevd.81.103002

Cited by 148 publications

(259 citation statements)

References 57 publications

(125 reference statements)

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“…As in Ref. [36], we find no mass dependence of the velocity dispersion after scaling by the virial expectation, σ 2 ∝ M 2/3 . We also find no mass dependence of the ratio of the scaled nDGP velocity dispersion to that of the matched LCDM halos, shown in the left panel of Figure 11 for nDGP1, which has the most deviation from LCDM of the models we simulated.…”

Section: B Velocitiesmentioning

confidence: 54%

“…There appears to be no dependence of this ratio on either halo mass or morphological environment; the non-dependence on mass was previously confirmed by Ref. [36]. Since ORIGAMI halos contain particles well outside the virial radius, out to the outer phase-space caustic, we can also obtain ∆ M for each halo that includes the upturn in the ∆ M (r) profile in Figure 9.…”

Section: Fig 6: Same Asmentioning

confidence: 62%

“…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%

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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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Section: B Velocitiesmentioning

confidence: 54%

Section: Fig 6: Same Asmentioning

confidence: 62%

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The Vainshtein mechanism in the cosmic web

Falck

Koyama

Zhao

et al. 2014

J. Cosmol. Astropart. Phys.

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“…They are known to have very regular structure and dynamics, which can set constraints on gravity theories. The infall of galaxies onto massive systems like groups and clusters is a potential test, especially of theories that rely on Vainshtein screening -see Hui et al (2009), Schmidt (2010, and Jain (2011) for discussions. Observable properties of stars may also be altered by the enhanced forces in MG theories (Chang & Hui 2011;Davis et al 2011).…”

Section: Remaining Uncertainties and Further Workmentioning

confidence: 99%

Tests of modified gravity with dwarf galaxies

Jain

Vanderplas

2011

J. Cosmol. Astropart. Phys.

103

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In modified gravity theories that seek to explain cosmic acceleration, dwarf galaxies in low density environments can be subject to enhanced forces. The class of scalartensor theories, which includes f (R) gravity, predict such a force enhancement (massive galaxies like the Milky Way can evade it through a screening mechanism that protects the interior of the galaxy from this "fifth" force). We study observable deviations from GR in the disks of late-type dwarf galaxies moving under gravity. The fifth-force acts on the dark matter and HI gas disk, but not on the stellar disk owing to the self-screening of main sequence stars. We find four distinct observable effects in such disk galaxies: 1. A displacement of the stellar disk from the HI disk. 2. Warping of the stellar disk along the direction of the external force. 3. Enhancement of the rotation curve measured from the HI gas compared to that of the stellar disk. 4. Asymmetry in the rotation curve of the stellar disk. We estimate that the spatial effects can be up to 1 kpc and the rotation velocity effects about 10 km/s in infalling dwarf galaxies. Such deviations are measurable: we expect that with a careful analysis of a sample of nearby dwarf galaxies one can improve astrophysical constraints on gravity theories by over three orders of magnitude, and even solar system constraints by one order of magnitude. Thus effective tests of gravity along the lines suggested by Hui et al. (2009) and Jain (2011) can be carried out with low-redshift galaxies, though care must be exercised in understanding possible complications from astrophysical effects.

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“…Instead of studying the screening mechanism based on individual isolated galactic haloes [18][19][20], we examine the relation between the scalar field, δf R , and the gravitational potential, ϕ, in fðRÞ cosmologies, using N-body simulations. We demonstrate that this relation plays an important role in understanding the screening mechanism in fðRÞ gravity.…”

Section: Introductionmentioning

confidence: 99%

Revisiting the screening mechanism inf(R)gravity

Hawken

et al. 2014

Phys. Rev. D

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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 DRO • 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.Please consult the full DRO policy for further details. We reexamine the screening mechanism in fðRÞ gravity using N-body simulations. By explicitly examining the relation between the extrascalar field δf R and the gravitational potential ϕ in the perturbed Universe, we find that the relation between these two fields plays an important role in understanding the screening mechanism. We show that the screening mechanism in fðRÞ gravity depends mainly on the depth of the potential well and find a useful condition for identifying unscreened haloes in simulations. We also discuss the potential application of our results to real galaxy surveys.

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Dynamical masses in modified gravity

Cited by 148 publications

References 57 publications

The Vainshtein mechanism in the cosmic web

The Vainshtein mechanism in the cosmic web

Tests of modified gravity with dwarf galaxies

Revisiting the screening mechanism inf(R)gravity

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