Newtonian kinematical backreaction in cosmological <i>N</i>-body simulations with Delaunay Tesselation: “Zero test” and scale dependence

Kazimierczak, Tomasz A.

doi:10.1142/9789813226609_0272

Cited by 2 publications

(2 citation statements)

References 3 publications

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“…Estimates of the backreaction have been so far addressed either within the fluid formalism: e.g. [26] and [27] or within the N-body codes but on the global scale: [28]. With the maximum volume approach, we can test the predictions of the averaged scalar equations together with the RZA serving as a closure condition by looking at the scales of clusters and super-clusters in the N-body simulations.…”

Section: Applicationsmentioning

confidence: 99%

On the maximum volume of collapsing structures

Ostrowski

Gaspar

2022

J. Cosmol. Astropart. Phys.

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In many cosmological models, including the ΛCDM concordance model, there exist theoretical upper bounds on the size of collapsing structures. The most common formulations in the literature refer to a turnaround radius in spherical symmetry or a turnaround surface, defined as the zero-expansion boundary separating the outer Hubble flow from the inner flow of a collapsing fluid. In order to access a generic scenario, we propose an improvement of this cosmological test in terms of the maximum volume of the cosmological structures, which is equivalent to a zero-averaged expansion — instead of the zero-local expansion. By combining the Lagrangian perturbations method and the scalar averaging of Einstein's equations, we obtain a maximum volume for a collapse model without any restricting symmetries. We compare this result with some exact, inhomogeneous solutions and discuss further potential developments.

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Section: Applicationsmentioning

confidence: 99%

On the maximum volume of collapsing structures

Ostrowski

Gaspar

2022

J. Cosmol. Astropart. Phys.

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“…applying post-Newtonian corrections) suggest that the mean evolution is well approximated by the Friedmannian evolution [6][7][8]. On the other hand, studies that try to implement backreaction-type effects into the Newtonian Cosmology and N -body codes find large effects [9,10] -such an approach has sparked recently a debate, see Ref. [11] and the rebuttal response in Ref.…”

Section: Introductionmentioning

confidence: 99%

Cosmological backreaction within the Szekeres model and emergence of spatial curvature

Bolejko

2017

J. Cosmol. Astropart. Phys.

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This paper discusses the phenomenon of backreaction within the Szekeres model.Cosmological backreaction describes how the mean global evolution of the Universe deviates from the Friedmannian evolution. The analysis is based on models of a single cosmological environment and the global ensemble of the Szekeres models (of the Swiss-Cheese-type and Styrofoam-type). The obtained results show that non-linear growth of cosmic structures is associated with the growth of the spatial curvature Ω R (in the FLRW limit Ω R → Ω k ). If averaged over global scales the result depends on the assumed global model of the Universe. Within the Swiss-Cheese model, which does have a fixed background, the volume average follows the evolution of the background, and the global spatial curvature averages out to zero (the background model is the ΛCDM model, which is spatially flat). In the Styrofoamtype model, which does not have a fixed background, the mean evolution deviates from the spatially flat ΛCDM model, and the mean spatial curvature evolves from Ω R = 0 at the CMB to Ω R ∼ 0.1 at z = 0. If the Styrofoam-type model correctly captures evolutionary features of the real Universe then one should expect that in our Universe, the spatial curvature should build up (local growth of cosmic structures) and its mean global average should deviate from zero (backreaction). As a result, this paper predicts that the low-redshift Universe should not be spatially flat (i.e. Ω k = 0, even if in the early Universe Ω k = 0) and therefore when analysing low-z cosmological data one should keep Ω k as a free parameter and independent from the CMB constraints.

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Newtonian kinematical backreaction in cosmological N-body simulations with Delaunay Tesselation: “Zero test” and scale dependence

Cited by 2 publications

References 3 publications

On the maximum volume of collapsing structures

On the maximum volume of collapsing structures

Cosmological backreaction within the Szekeres model and emergence of spatial curvature

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