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Cosmic voids, the large underdense regions of our Universe, have emerged over the past decade as powerful cosmological laboratories: their simple dynamics, sensitivity to local gravitational effects and cosmic expansion, and ability to span…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-22 Sofia Contarini , Giovanni Verza , Alice Pisani

Conditions for smooth cosmological models are set out and applied to inhomogeneous spherically symmetric models constructed by matching together different Lemaitre-Tolman-Bondi solutions to the Einstein field equations. As an illustration…

General Relativity and Quantum Cosmology · Physics 2015-06-25 D. R. Matravers , N. P. Humphreys

The inhomogeneous distribution of matter in the non-linear regime of galaxies, clusters of galaxies and voids is described by an exact, spherically symmetric inhomogeneous solution of Einstein's gravitational field equations, corresponding…

Astrophysics · Physics 2009-11-11 J. W. Moffat

Theoretical and observational challenges to standard cosmology such as the cosmological constant problem and tensions between cosmological model parameters inferred from different observations motivate the development and search of new…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-30 Lucas Lombriser

The current standard model of cosmology, the LambdaCDM model, is based on the homogeneous FLRW solutions of the Einstein equations to which some perturbations are added to account for the CMB features and structure formation at large…

Cosmology and Nongalactic Astrophysics · Physics 2012-03-14 Marie-Noëlle Célérier

Recent observational analyses have suggested possible evidence of hemisphere asymmetry in cosmological datasets. Parameterizations of this kind place observers in a privileged position-specifically on the plane that divides the two…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-16 Xin Wang , Zhiqi Huang

This paper presents the cosmological applications of the quasispherical Szekeres model. The quasispherical Szekeres model is an exact solution of the Einstein field equations, which represents a time-dependent mass dipole superposed on a…

Astrophysics · Physics 2007-05-23 Krzysztof Bolejko

We compare analytical predictions of void volume functions to those measured from N-body simulations, detecting voids with the zobov void finder. We push to very small, nonlinear voids, below few Mpc radius, by considering the unsampled DM…

Cosmology and Nongalactic Astrophysics · Physics 2015-07-06 Ixandra Achitouv , Mark Neyrinck , Aseem Paranjape

It is commonly stated that we have entered the era of precision cosmology in which a number of important observations have reached a degree of precision, and a level of agreement with theory, that is comparable with many Earth-based physics…

General Physics · Physics 2011-10-31 Marie-Noëlle Célérier

An analytical model for the postcollapse equilibrium structure of virialized objects which condense out of the cosmological background universe is described and compared with observations and simulations of cosmological halos. The model is…

Astrophysics · Physics 2007-05-23 Ilian T. Iliev , Paul R. Shapiro

While the topology of the Universe is at present not specified by any known fundamental theory, it may in principle be determined through observations. In particular, a non-trivial topology will generate pairs of matching circles of…

Astrophysics · Physics 2010-04-21 B. Mota , M. J. Reboucas , R. Tavakol

We construct the first exact statistically homogeneous and isotropic cosmological solution in which inhomogeneity has a significant effect on the expansion rate. The universe is modelled as a Swiss Cheese, with dust FRW background and…

Cosmology and Nongalactic Astrophysics · Physics 2014-01-08 Mikko Lavinto , Syksy Rasanen , Sebastian J. Szybka

Studies of disordered heterogeneous media and galaxy cosmology share a common goal: analyzing the distribution of particles at `microscales' to predict physical properties at `macroscales', whether for a liquid, composite material, or…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-11 Oliver H. E. Philcox , Salvatore Torquato

Using the exact Lemaitre-Bondi-Tolman solution with a non-vanishing cosmological constant $\Lambda$, we investigate how the presence of a local spherically-symmetric inhomogeneity can affect apparent cosmological observables, such as the…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-01 Antonio Enea Romano , Misao Sasaki , Alexei A. Starobinsky

The observational behavior of spherically symmetric inhomogeneous cosmological models is studied, which consist of inner and outer homogeneous regions connected by a shell or an intermediate self-similar region. It is assumed that the…

Astrophysics · Physics 2009-10-31 Kenji Tomita

The anisotropies of the cosmic microwave background (CMB) are computed for the half-turn space E_2 which represents a compact flat model of the Universe, i.e. one with finite volume. This model is inhomogeneous in the sense that the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 R. Aurich , S. Lustig

Light is affected by local inhomogeneities in its propagation, which may alter distances and so cosmological parameter estimation. In the era of precision cosmology, the presence of inhomogeneities may induce systematic errors if not…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-11 J. A. S. Lima , V. C. Busti , R. C. Santos

On the largest scales, the universe appears to be almost homogeneous and isotropic, adhering to the cosmological principle. In contrast, on smaller scales inhomogeneities and anisotropy become increasingly prominent, reflecting the origin,…

General Relativity and Quantum Cosmology · Physics 2025-10-07 Robbert W. Scholtens , Marcello Seri , Holger Waalkens , Rien van de Weygaert

In order to quantitatively test the ability of averaged inhomogeneous cosmologies to correctly describe observations of the large scale properties of the Universe, we introduce a smoothed template metric corresponding to a constant spatial…

We briefly report on a previously found new, approximate, solution to Einstein field equations, describing a cubic lattice of spherical masses. This model mimics in a satisfactory way a Universe which can be strongly inhomogeneous at small…

General Relativity and Quantum Cosmology · Physics 2013-03-04 Jean-Philippe Bruneton
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