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Friedmann–Lemaître–Robertson–Walker metric

About: Friedmann–Lemaître–Robertson–Walker metric is a research topic. Over the lifetime, 4113 publications have been published within this topic receiving 87752 citations. The topic is also known as: FLRW metric.


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TL;DR: In this article, the authors investigated the implications of energy conditions on cosmological compactification solutions of higher-dimensional Einstein field equations and showed that the same assumptions allow compactification to FLRW universes undergoing late-time accelerated expansion.
Abstract: We investigate the implications of energy conditions on cosmological compactification solutions of the higher-dimensional Einstein field equations. It is known that the strong energy condition forbids time-independent compactifications to de Sitter space but allows time-dependent compactifications to other (homogeneous and isotropic) expanding universes that undergo a transient period of acceleration. Here we show that the same assumptions allow compactification to FLRW universes undergoing late-time accelerated expansion; the late-time stress tensor is a perfect fluid but with a lower bound on the pressure/energy-density ratio that excludes de Sitter but allows accelerated power-law expansion. The compact space undergoes a decelerating expansion that leads to decompactification, but on an arbitrarily long timescale.

27 citations

Journal ArticleDOI
TL;DR: In this paper, a method for generating exact solutions of the equations of the scalar field dynamics in the case of flat Friedmann-Robertson-Walker space on the basis of form-invariant transformations is considered.
Abstract: A method for generating exact solutions of the equations of the scalar field dynamics in the case of flat Friedmann–Robertson–Walker space on the basis of form-invariant transformations is considered. A method for estimating the divergence of the exact and approximate solutions from the number of e-folds and the parameters of the cosmological perturbations is proposed.

27 citations

Journal ArticleDOI
TL;DR: In this article, the authors examined static perfect fluid spheres in the presence of a cosmological constant and derived conditions depending on the equation of state to locate the vanishing pressure surface, which can be located in regions where, going outwards, the area of the spheres associated with the group of spherical symmetry is decreasing.
Abstract: We examine static perfect fluid spheres in the presence of a cosmological constant. Because of the cosmological constant, new classes of exact matter solutions are found. One class of solutions requires the Nariai metric in the vacuum region. Another class generalizes the Einstein static universe such that neither its energy density nor its pressure is constant throughout the spacetime. Using analytical techniques we derive conditions depending on the equation of state to locate the vanishing pressure surface. This surface can, in general, be located in regions where, going outwards, the area of the spheres associated with the group of spherical symmetry is decreasing. We use numerical methods to integrate the field equations for realistic equations of state and find consistent results.

27 citations

Journal ArticleDOI
TL;DR: In this paper, a generalization of two-field α-attractors with a positive constant α was proposed, where the scalar manifold is a non-compact geometrically finite surface with a Riemannian metric.

27 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the dynamics of a flat FRW cosmological model with a barotropic matter and a non-minimally coupled scalar field (both canonical and phantom).
Abstract: We investigate dynamics of a flat FRW cosmological model with a barotropic matter and a non-minimally coupled scalar field (both canonical and phantom). In our approach we do not assume any specific form of a potential function for the scalar field and we are looking for generic scenarios of evolution. We show that dynamics of universe can be reduced to a 3-dimensional dynamical system. We have found the set of fixed points and established their character. These critical points represent all important epochs in evolution of the universe: (a) a finite scale factor singularity, (b) an inflation (rapid-roll and slow-roll), (c) a radiation domination, (d) a matter domination and (e) a quintessence era. We have shown that the inflation, the radiation and matter domination epochs are transient ones and last for a finite amount of time. The existence of the radiation domination epoch is purely the effect of a non-minimal coupling constant. We show the existence of a twister type solution wandering between all these critical points.

27 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023150
2022352
2021196
2020204
2019214
2018191