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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 paper, the authors investigated the dynamics of a flat FRW cosmological model with a non-minimally coupled scalar field with the coupling term R \xi R \psi^{2}$ in the scalar fields action.
Abstract: In this publication we investigate dynamics of a flat FRW cosmological model with a non-minimally coupled scalar field with the coupling term $\xi R \psi^{2}$ in the scalar field action. The quadratic potential function $V(\psi)\propto \psi^{2}$ is assumed. All the evolutional paths are visualized and classified in the phase plane, at which the parameter of non-minimal coupling $\xi$ plays the role of a control parameter. The fragility of global dynamics with respect to changes of the coupling constant is studied in details. We find that the future big rip singularity appearing in the phantom scalar field cosmological models can be avoided due to non-minimal coupling constant effects. We have shown the existence of a finite scale factor singular point (future or past) where the Hubble function as well as its first cosmological time derivative diverges.

43 citations

Journal ArticleDOI
TL;DR: In this article, the background metric tensor is chosen on the basis of a model of the universe, in accordance with the perfect cosmological principle, it is taken as describing a space-time of constant curvature.
Abstract: In the bimetric theory of gravitation the background metric tensor γ μν , previously taken as describing flat space-time, is now chosen on the basis of a model of the universe. In accordance with the perfect cosmological principle, it is taken as describing a space-time of constant curvature. There are three possible forms, corresponding tok=0, 1, −1. Only fork=1 (a closed universe) does the model not go through a singular state; hence this is the appropriate choice. The isotropic solution of the field equations can be chosen to agree with the present cosmological observations. For small systems like the solar system the theory gives the same results as before, in agreement with those of general relativity.

43 citations

Journal ArticleDOI
TL;DR: In this paper, the dissipative dynamics of an expanding massless gas with constant cross section in a spatially flat Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) universe is studied.
Abstract: The dissipative dynamics of an expanding massless gas with constant cross section in a spatially flat Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) universe is studied. The mathematical problem of solving the full nonlinear relativistic Boltzmann equation is recast into an infinite set of nonlinear ordinary differential equations for the moments of the one-particle distribution function. Momentum-space resolution is determined by the number of nonhydrodynamic modes included in the moment hierarchy, i.e., by the truncation order. We show that in the FLRW spacetime the nonhydrodynamic modes decouple completely from the hydrodynamic degrees of freedom. This results in the system flowing as an ideal fluid while at the same time producing entropy. The solutions to the nonlinear Boltzmann equation exhibit transient tails of the distribution function with nontrivial momentum dependence. The evolution of this tail is not correctly captured by the relaxation time approximation nor by the linearized Boltzmann equation. However, the latter probes additional high-momentum details unresolved by the relaxation time approximation. While the expansion of the FLRW spacetime is slow enough for the system to move towards (and not away from) local thermal equilibrium, it is not sufficiently slow for the system to actually ever reach complete local equilibrium. Equilibration is fastest in the relaxation time approximation, followed, in turn, by kinetic evolution with a linearized and a fully nonlinear Boltzmann collision term.

43 citations

Journal ArticleDOI
TL;DR: In this article, the authors consider the compactification of pure gravity and superstring theory on an n-dimensional internal space to a d-dimensional Friedmann-Lema-tre-Robertson-Walker cosmology, with a spatial curvature $k=0, ifmmode\pm/pm\else\textpm\fi{}1,$ in the Einstein conformal frame.
Abstract: We consider the compactification of $(d+n)$-dimensional pure gravity and of superstring or M-theory on an n-dimensional internal space to a d-dimensional Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) cosmology, with a spatial curvature $k=0,\ifmmode\pm\else\textpm\fi{}1,$ in the Einstein conformal frame. The internal space is taken to be a product of Einstein spaces, each of which is allowed to have arbitrary curvature and a time-dependent volume. By investigating the effective d-dimensional scalar potential, which is a sum of exponentials, it is shown that such compactifications, in the $k=0,+1$ cases, do not lead to large amounts of accelerating expansion of the scale factor of the resulting FLRW universe, and, in particular, do not lead to inflation. The case $k=\ensuremath{-}1$ admits solutions with eternal accelerating expansion for which the acceleration, however, tends to zero at late times.

43 citations

Journal ArticleDOI
TL;DR: A link is made between the existence of gravitational-wave modes and the conformal curvature of hypersurfaces in spacetime and how these results can be useful in the analysis of exact solutions of the Einstein field equations.
Abstract: We use Bardeen's gauge-invariant formalism to analyze the behavior of, and relationship between, various geometric and physical quantities of cosmological interest at the linear level. This leads to a cosmologically oriented gauge-invariant characterization of the different perturbation modes that can arise. In particular a link is made between the existence of gravitational-wave modes and the conformal curvature of hypersurfaces in spacetime. We indicate how these results can be useful in the analysis of exact solutions of the Einstein field equations.

42 citations


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