Light propagation and large-scale inhomogeneities

Brouzakis, N.; Tetradis, N.; Tzavara, Eleftheria

doi:10.1088/1475-7516/2008/04/008

Cited by 78 publications

(120 citation statements)

References 62 publications

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“…The optical properties of such models have been extensively studied (see Refs. [54][55][56][57][58][59][60][61][62]) to finally conclude that the average luminosityredshift relation remains unchanged with respect to the purely homogeneous case, contrary to the early results of Refs. [52,53].…”

Section: Figcontrasting

confidence: 86%

“…It has been proven in Refs. [58,61,62] that the global effect averages to zero when many sources are considered. Hence, LTB holes introduce an additional dispersion to the Hubble diagram, but no statistically significant bias.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…VI D, such a claim was proven to be inaccurate in Refs. [57,58,62], because it relies on observations along a peculiar line of sight. When many random directions of observation are taken into account, the mean magnification goes back to 1.…”

Section: Comparison With Other Recent Studiesmentioning

confidence: 99%

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Interpretation of the Hubble diagram in a nonhomogeneous universe

Fleury¹,

Dupuy²,

Uzan³

2013

Phys. Rev. D

130

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In the standard cosmological framework, the Hubble diagram is interpreted by assuming that the light emitted by standard candles propagates in a spatially homogeneous and isotropic spacetime. However, the light from "point sources"-such as supernovae-probes the Universe on scales where the homogeneity principle is no longer valid. Inhomogeneities are expected to induce a bias and a dispersion of the Hubble diagram. This is investigated by considering a Swiss-cheese cosmological model, which (1) is an exact solution of the Einstein field equations, (2) is strongly inhomogeneous on small scales, but (3) has the same expansion history as a strictly homogeneous and isotropic universe. By simulating Hubble diagrams in such models, we quantify the influence of inhomogeneities on the measurement of the cosmological parameters. Though significant in general, the effects reduce drastically for a universe dominated by the cosmological constant.

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Section: Figcontrasting

confidence: 86%

Section: Summary and Discussionmentioning

confidence: 99%

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Interpretation of the Hubble diagram in a nonhomogeneous universe

Fleury¹,

Dupuy²,

Uzan³

2013

Phys. Rev. D

130

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“…Other similar studies are those of Brouzakis, Tetradis & Tzavara [29] and Biswas & Notari [33]. Brouzakis to R = 40 Mpc voids at z s = 1.…”

Section: Discussionsupporting

confidence: 74%

Luminosity distance in “Swiss cheese” cosmology with randomized voids. II. Magnification probability distributions

2012

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We study the fluctuations in luminosity distances due to gravitational lensing by large scale ( 35 Mpc) structures, specifically voids and sheets. We use a simplified "Swiss cheese" model consisting of a ΛCDM Friedman-Robertson-Walker background in which a number of randomly distributed non-overlapping spherical regions are replaced by mass compensating comoving voids, each with a uniform density interior and a thin shell of matter on the surface. We compute the distribution of magnitude shifts using a variant of the method of Holz & Wald (1998), which includes the effect of lensing shear. The standard deviation of this distribution is ∼ 0.027 magnitudes and the mean is ∼ 0.003 magnitudes for voids of radius 35 Mpc, sources at redshift zs = 1.0, with the voids chosen so that 90% of the mass is on the shell today. The standard deviation varies from 0.005 to 0.06 magnitudes as we vary the void size, source redshift, and fraction of mass on the shells today. If the shell walls are given a finite thickness of ∼ 1 Mpc, the standard deviation is reduced to ∼ 0.013 magnitudes. This standard deviation due to voids is a factor ∼ 3 smaller than that due to galaxy scale structures. We summarize our results in terms of a fitting formula that is accurate to ∼ 20%, and also build a simplified analytic model that reproduces our results to within ∼ 30%. Our model also allows us to explore the domain of validity of weak lensing theory for voids. We find that for 35 Mpc voids, corrections to the dispersion due to lens-lens coupling are of order ∼ 4%, and corrections to due shear are ∼ 3%. Finally, we estimate the bias due to source-lens clustering in our model to be negligible.

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“…The most common examples are Swiss-cheese models [23,24], where inhomogeneities are introduced within a background FL spacetime by inserting spherical patches of another exact solution of Einstein's equation. Recent analyses generally exploit the Lemaître-Tolman-Bondi (LTB) [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] or Szekeres [40][41][42][43] geometries as interior solutions, which aim at describing large-scale inhomogeneities such as superclusters or cosmic voids (see also Refs. [44,45]).…”

Section: Introductionmentioning

confidence: 99%

The theory of stochastic cosmological lensing

Fleury

Larena

Uzan

2015

J. Cosmol. Astropart. Phys.

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Abstract. On the scale of the light beams subtended by small sources, e.g. supernovae, matter cannot be accurately described as a fluid, which questions the applicability of standard cosmic lensing to those cases. In this article, we propose a new formalism to deal with small-scale lensing as a diffusion process: the Sachs and Jacobi equations governing the propagation of narrow light beams are treated as Langevin equations. We derive the associated FokkerPlanck-Kolmogorov equations, and use them to deduce general analytical results on the mean and dispersion of the angular distance. This formalism is applied to random Einstein-Straus Swiss-cheese models, allowing us to: (1) show an explicit example of the involved calculations; (2) check the validity of the method against both ray-tracing simulations and direct numerical integration of the Langevin equation. As a byproduct, we obtain a post-Kantowski-DyerRoeder approximation, accounting for the effect of tidal distortions on the angular distance, in excellent agreement with numerical results. Besides, the dispersion of the angular distance is correctly reproduced in some regimes.ArXiv ePrint: 1508.07903 arXiv:1508.07903v2 [gr-qc]

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Light propagation and large-scale inhomogeneities

Cited by 78 publications

References 62 publications

Interpretation of the Hubble diagram in a nonhomogeneous universe

Interpretation of the Hubble diagram in a nonhomogeneous universe

Luminosity distance in “Swiss cheese” cosmology with randomized voids. II. Magnification probability distributions

The theory of stochastic cosmological lensing

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