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We obtain an elegant and useful description of the dynamics of Szekeres dust models (in their full generality) by means of `quasi-local' scalar variables constructed by suitable integral distributions that can be interpreted as weighed…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Roberto A. Sussman , Krzysztof Bolejko

The Szekeres family of inhomogeneous solutions, which are defined by six arbitrary metric functions, offers a wide range of possibilities for modelling cosmic structure. Here we present a model construction procedure for the quasispherical…

General Relativity and Quantum Cosmology · Physics 2015-06-12 Anthony Walters , Charles Hellaby

In view of interpreting the cosmological observations precisely, especially when they involve narrow light beams, it is crucial to understand how light propagates in our statistically homogeneous, clumpy, Universe. Among the various…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-26 Pierre Fleury

Exact inhomogeneous solutions of Einstein's equations have been used in the literature to build models reproducing the cosmological data without dark energy. However, owing to the degrees of freedom pertaining to these models, it is…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-29 Priti Mishra , Marie-Noëlle Célérier , Tejinder P. Singh

The simplest standard ray tracing scheme employing the Born and Limber approximations and neglecting lens-lens coupling is used for computing the convergence along individual rays in mock N-body data based on Szekeres swiss cheese and onion…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-05 S. M. Koksbang , S. Hannestad

We consider an extension of a special class of conformal sigma models (`chiral null models') which describe extreme supersymmetric string solutions. The new models contain both `left' and `right' vector couplings and should correspond to…

High Energy Physics - Theory · Physics 2009-09-17 A. A. Tseytlin

We study the differences and equivalences between the non-perturbative description of the evolution of cosmic structure furnished by the Szekeres dust models (a non-spherical exact solution of Einstein's equations) and the dynamics of…

General Relativity and Quantum Cosmology · Physics 2017-04-05 Roberto A. Sussman , Juan Carlos Hidalgo , Ismael Delgado Gaspar , Gabriel German

An overview of some recent developments in inhomogeneous models is presented. As the volume and precision of cosmological data improves, it will become more and more essential to understand the non-linear behaviour of the Einstein field…

General Relativity and Quantum Cosmology · Physics 2010-01-06 Charles Hellaby

The equations of the 1+3 orthonormal frame approach are explicitly presented and discussed. Natural choices of local coordinates are mentioned. A dimensionless formulation is subsequently given. It is demonstrated how one can obtain a…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Henk van Elst , Claes Uggla

We lay out a general framework for calculating the variation of a set of cosmological observables, down the past null cone of an arbitrarily placed observer, in a given arbitrary inhomogeneous metric. The observables include redshift,…

General Relativity and Quantum Cosmology · Physics 2018-02-21 Charles Hellaby , Anthony Walters

To use strong gravitational lenses as an astrophysical or cosmological probe, models of their mass distributions are often needed. We present a new, time-efficient automation code for uniform modeling of strongly lensed quasars with GLEE, a…

Cosmology and Nongalactic Astrophysics · Physics 2023-03-29 S. Ertl , S. Schuldt , S. H. Suyu , T. Schmidt , T. Treu , S. Birrer , A. J. Shajib , D. Sluse

We present a tetrad-based method for solving the Einstein field equations for spherically-symmetric systems and compare it with the widely-used Lema\^itre-Tolman-Bondi (LTB) model. In particular, we focus on the issues of gauge ambiguity…

General Relativity and Quantum Cosmology · Physics 2016-04-22 Do Young Kim , Anthony N. Lasenby , Michael P. Hobson

Spherically symmetric dust universe models with a positive cosmological constant $\Lambda$, known as $\Lambda$-Lema\^itre-Tolman-Bondi($\Lambda$LTB) models, are considered. We report a method to construct the $\Lambda$LTB model from a given…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-12 Masato Tokutake , Chul-Moon Yoo

The status of the standard cosmological model, also known as "LCDM" is described. With some simple assumptions, this model fits a wide range of data, with just six (or seven) free parameters. One should be skeptical about this claim, since…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-05 Douglas Scott

The exact Friedman solution to the field equations of General Relativity (GR) describing a homogeneous and isotropic universe together with its linear and higher-order perturbations are the theoretical roots of the current standard model of…

General Relativity and Quantum Cosmology · Physics 2024-12-20 Marie-Noëlle Célérier

We examine the correspondence between QFT observables and bulk solutions in the context of AdS/CFT in the limit as the cosmological constant $\Lambda \to 0$. We focus specifically on the spacetime metric and a non-backreacting scalar in the…

High Energy Physics - Theory · Physics 2014-11-26 R. N. Caldeira Costa

We show that the Szekeres system with cosmological constant admits a sufficient number of conservation laws, which allow to claim the integrability of the system. The main novelty in this investigation is that we find that the unique…

General Relativity and Quantum Cosmology · Physics 2021-08-11 Adamantia Zampeli , Andronikos Paliathanasis

Following recent considerations of a non-zero value for the vacuum energy density and the realization that a simple Kantowski-Sachs model might fit the classical tests of cosmology, we study the qualitative behavior of three anisotropic and…

Astrophysics · Physics 2011-04-15 Paulo Aguiar , Paulo Crawford

This paper is the third of a series dedicated to the study of the Delayed Big-Bang (DBB) class of inhomogeneous cosmological models of Lema\^itre-Tolman-Bondi type. In the first work, it was shown that the geometrical properties of the DBB…

General Relativity and Quantum Cosmology · Physics 2011-05-23 Marie-Noëlle Célérier

One of the most important discoveries in cosmology is the accelerated expansion of the Universe. Yet, the accelerated expansion has only ever been measured {\em in}directly. Redshift drift offers a direct observational probe of the…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-31 David Rønne Sallingboe , Sofie Marie Koksbang