Example of an inhomogeneous cosmological model in the context of backreaction

Sikora, Szymon; Głód, Krzysztof

doi:10.1103/physrevd.95.063517

Cited by 18 publications

(22 citation statements)

References 28 publications

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“…Then, we consider the resulting fourth-order metric as the polynomial in the perturbative parameter and calculate the exact Einstein tensor. This way, we analyze the higher-order contributions, what is the main improvement compared to our previous papers [77,78]. We interpret the pressure-like terms of the energymomentum tensor in the framework of the Jeans' theory of the collisionless system of particles.…”

Section: Conlusionsmentioning

confidence: 95%

“…3.2 that for a large amplitude of the inhomogeneities considered, the third-order perturbations do not satisfy the observational constraints of the pressure value in the matter-dominated era, while the fourth-order model does. This way, we investigate the convergence of our perturbative framework, which is an improvement compared to our previous papers [77,78].…”

Section: Exact Solutionmentioning

confidence: 99%

“…The principal goal of this paper is to find a cosmological model which remains dust-like within the observational constraints, but at the same time allows much higher amplitude of the inhomogeneities than the linear perturbation theory. We studied decaying mode of the linear perturbation theory in [77] and expanded it to the third-order perturbations in [78]. In the recent paper, we consider the growing mode of the perturbation theory up to the fourth order.…”

Section: Supplementary Informationmentioning

confidence: 99%

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Construction of the cosmological model with periodically distributed inhomogeneities with growing amplitude

Sikora

Głód

2021

Eur. Phys. J. C

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We construct an approximate solution to the cosmological perturbation theory around Einstein–de Sitter background up to the fourth-order perturbations. This could be done with the help of the specific symmetry condition imposed on the metric, from which follows that the model density forms an infinite, cubic lattice. To verify the convergence of the perturbative construction, we express the resulting metric as a polynomial in the perturbative parameter and calculate the exact Einstein tensor. In our model, it seems that physical quantities averaged over large scales overlap with the respective Einstein–de Sitter prediction, while local observables could differ significantly from their background counterparts. As an example, we analyze the behavior of the local measurements of the Hubble constant and compare them with the Hubble constant of the homogeneous background model. A difference between these quantities is important in the context of a current Hubble tension problem.

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Section: Conlusionsmentioning

confidence: 95%

Section: Exact Solutionmentioning

confidence: 99%

Section: Supplementary Informationmentioning

confidence: 99%

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Construction of the cosmological model with periodically distributed inhomogeneities with growing amplitude

Sikora

Głód

2021

Eur. Phys. J. C

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“…The procedure of the angular diameter distance-redshift relation derivation is similar to that in the paper [39]. We will locate the observer in the three different positions: in the overdensity xO = ( π 2 , π 2 , π 2 ), in the underdensity xU = (0, 0, 0) and at some point somewhere in between xM = (0.7, 1.1, 2.1), and in the two time instants t is Ω = 1.067, so it is the point with a slightly higher density than the average.…”

Section: The Light Propagationmentioning

confidence: 99%

“…In our previous paper [39] we constructed within the linear perturbation theory a simple model of the dust inhomogeneities on the Einstein-de Sitter (EdS) background. These inhomogeneities form an infinite, periodic, cubic lattice presented in Fig.…”

Section: Introductionmentioning

confidence: 99%

Perturbatively constructed cosmological model with periodically distributed dust inhomogeneities

Sikora

Głód

2019

Phys. Rev. D

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We constructed a simple cosmological model which approximates the Einstein-de Sitter background with periodically distributed dust inhomogeneities. By taking the metric as a power series up to the third order in some perturbative parameter λ, we are able to achieve large values of the density contrast. With a metric explicitly given, many model properties can be calculated in a straightforward way which is interesting in the context of the current discussion concerning the averaging of the inhomogeneities and their backreaction in cosmology. Although the Einstein-de Sitter model can be thought as the model average, the light propagation differs from that of the Einstein-de Sitter. The angular diameter distance-redshift relation is affected by the presence of inhomogeneities and depends on the observer's position. The model construction scheme enables some generalizations in the future, so the present work is a step towards more realistic cosmological model described by a relatively simple analytical metric.

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