Turnaround radius in <i>f</i>(<i>R</i>) model

Lopes, Rafael C. C.; Voivodic, Rodrigo; Abramo, L. Raul; Sodré, L.

doi:10.1088/1475-7516/2018/09/010

Cited by 30 publications

(85 citation statements)

References 49 publications

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“…(26), the correction −φ N R (HR) 2 is neglected for structures of size R much smaller than the Hubble radius (this term is of second order in R/H −1 ). The current literature on the turnaround radius is restricted to this spherical situation [12][13][14][15][24][25][26][27][28][29][30][31]. In this context, the turnaround radius is obtained when the "local" and the "cosmological" contributions to the right hand side of Eq.…”

Section: Turnaround Size Of a Large Structurementioning

confidence: 99%

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Turnaround size of non-spherical structures

Giusti

Faraoni

2019

Physics of the Dark Universe

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The turnaround radius of a large structure in an accelerating universe has been studied only for spherical structures, while real astronomical systems deviate from spherical symmetry. We show that, for small deviations from spherical symmetry, the gauge-invariant characterization of the turnaround size using the Hawking-Hayward quasi-local mass and spherical symmetry still applies, to first order in the cosmological perturbation potentials and in the deviations from sphericity. This is the first step to include non-spherical systems in the physics of turnaround. *

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Section: Turnaround Size Of a Large Structurementioning

confidence: 99%

“…The turnaround radius has been discussed also in alternative theories of gravity (see e.g. [24][25][26][27][28][29][30][31]), but in this work we focus solely on the standard GR picture. Thus far, the literature on the turnaround radius has studied only spherical structures.…”

Section: Introductionmentioning

confidence: 99%

Turnaround size of non-spherical structures

Giusti

Faraoni

2019

Physics of the Dark Universe

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“…Previous works have estimated these corrections to be of the order of a few percentage points at z 0; see [32] for results in symmetron gravity and [37] for similar results in f (R) theory. In particular, we expect our assumption to first break at a redshift z such that the condition F ϕ (r) ∼ F N (r) is satisfied at the turnaround radius r = R(t).…”

Section: Discussionmentioning

confidence: 90%

“…While deriving self-consistent solutions is outside the scope of this paper and more suited to N -body simulation studies, we find it useful to discuss the impact of our assumptions on the results. Changes to the turnaround physics are commonly studied through the use of different approximations, like a scale dependent New-ton's constant [33][34][35][36][37]. In our case, if we maintain the assumptions of self-similarity and power-law accretion in Eq.…”

Section: Discussionmentioning

confidence: 99%

Splashback radius in symmetron gravity

2019

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The splashback radius rsp has been identified in cosmological N -body simulations as an important scale associated with gravitational collapse and the phase-space distribution of recently accreted material. We employ a semi-analytical approach to study the spherical collapse of dark matter haloes in symmetron gravity and provide insights into how the phenomenology of splashback is affected. The symmetron is a scalar-tensor theory of gravity which exhibits a screening mechanism whereby higher-density regions are screened from the effects of a fifth force. In this model, we find that, as over-densities grow over cosmic time, the inner region becomes heavily screened. In particular, we identify a sector of the parameter space for which material currently sitting at rsp has followed, during the collapse, the formation of this screened region. As a result, we find that for this part of the parameter space the splashback radius is maximally affected by the symmetron force and we predict changes in rsp up to around 10% compared to its General Relativity value. Because this margin is within the precision of present splashback experiments, we expect this feature to soon provide constraints for symmetron gravity on previously unexplored scales. * contigiani@lorentz.leidenuniv.nl † vardanyan@lorentz.leidenuniv.nl ‡ silvestri@lorentz.leidenuniv.nl arXiv:1812.05568v1 [astro-ph.CO]

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“…The main results of this approach were presented in [30], but in that paper we expressed the turnaround radius as a function of turnaround mass, not in terms of the virial mass. While the two should be related, the virial mass is much more accessible to observations.…”

Section: Spherical Collapse In F (R)mentioning

confidence: 99%

Relation between the turnaround radius and virial mass in f(R) model

Lopes¹,

Voivodic²,

Abramo³

et al. 2019

J. Cosmol. Astropart. Phys.

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We investigate the relationship between the turnaround radius R t and the virial mass M v of cosmic structures in the context of ΛCDM model and in an f (R) model of modified gravity -namely, the Hu-Sawicki model. The turnaround radius is the distance from the center of the cosmic structure to the shell that is detaching from the Hubble flow at a given time, while the virial mass is defined, for this work, as the mass enclosed within the volume where the density is 200 times the background density. We employ a new approach by considering that, on average, gravitationally bound astrophysical systems (e.g., galaxies, groups and clusters of galaxies) follow, in their innermost region, a Navarro-Frenk-White density profile, while beyond the virial radius (R v ) the profile is well approximated by the 2-halo term of the matter correlation function. By combining these two properties together with the information drawn from solving the spherical collapse for the structures, we are able to connect two observables that can be readily measured in cosmic structures: the turnaround radius and the virial mass. In particular, we show that, in ΛCDM, the turnaround mass at z = 0 is related to the virial mass of that same structure by M t 3.07 M v , while in terms of the radii we have that R t 3.7 R v (for virial masses of 10 13 h −1 M ). In the f (R) model, on the other hand, we have M t 3.43 M v and R t 4.1 R v , for |f R0 | = 10 −6 and the same mass scale. Therefore, the difference between ΛCDM and f (R) in terms of these observable relations is of order ∼ 10−20% even for a relatively mild strength of the modification of gravity (|f R0 | = 10 −6 ). For the turnaround radius itself we find a difference of ∼ 9% between the weakly modification in gravity considered in this work (|f R0 | = 10 −6 ) and ΛCDM for a mass of 10 13 h −1 M . Once observations allow precisions of this order or better in measurements of the turnaround R t , as well as the virial mass M v (and/or the virial radius R v ), these quantities will become powerful tests of modified gravity.

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Turnaround radius in f(R) model

Cited by 30 publications

References 49 publications

Turnaround size of non-spherical structures

Turnaround size of non-spherical structures

Splashback radius in symmetron gravity

Relation between the turnaround radius and virial mass in f(R) model

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