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Showing 1 to 15 of 15 for “"Einstein field equations."”.
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Einstein constraints gluing and toroidal cusps
… mean curvature initial data sets to the vacuum Einstein Field Equations, obtaining new initial data on the joined manifold. The new data set is arbitrarily close to the original data set outside of the gluing region, controlled by the length of the neck joining the manifolds. This approach is …
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Even Parity Perturbations of the Janis-Newman-Winicour Singularity
… by gauge transformations. By calculating the Einstein field equations and the divergence of the stress-energy tensor, one obtains 8 independent radial equations for the first-order metric perturbations and scalar field perturbation. Through a suitable functional transformation, one can …
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Colapso gravitacional de fluido perfeito em espaços-tempos circularmente simétricos com auto-similaridade cinemática
… symmetry and various exact solutions to the Einstein field equations are given. These include all the solutions of dust and stiff perfect fluid with self-similarity of the first kind (homothetic) and all the solutions of perfect fluid with a linear equation of state and self-similarity of the …
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On Stability and Evolution of Solutions in General Relativity
… to the time evolution of the gravitational field. We present a formulation of the Einstein field equations in terms of variational techniques borrowed from geometric analysis. These equations yield the evolution equations for the Cauchy problems of both general relativity and low energy …
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Properties of Neutron Star Critical Collapses
… of the threshold in the solution space of the Einstein field equations between the black hole and a neutron star phases, and clarify the implication these results on realistic astrophysical scenarios. We develop a new set of neutron star-like initial data to establish the universality of the …
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The trial of the holographic principle
… whose conservation arises as a consequence of Einstein field equations of the dual black hole, is calculated via the Brown-York prescription augmented with renormalization of divergences. While the fluid-gravity idea is well-established, our careful analytic computation finds a form of the …
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On the evolution of large-scale structure in a cosmic void
… but inhomogeneous exact dust solutions to the Einstein field equations. They are known to accommodate most observations of the background universe without dark energy. In this work we present a new numerical code to solve the set of coupled partial differential equations that describe the …
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Discrete gravitational approaches to cosmology
Exact solutions to the Einstein field equations are notoriously difficult to find. Most known solutions describe systems with unrealistically high degrees of symmetry. A notable example is the FLRW metric underlying modern cosmology: the universe is assumed to be perfectly homogeneous and …
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A disformally coupled quintessence mimicking the ΛCDM background
… nature of the cosmological constant in the Einstein Field Equations, which is responsible for the accelerated cosmological expansion. Secondly, it cannot explain the σ8 tension, which occurs because the constraints upon galactic clustering by the Cosmic Microwave Background Planck …
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PERFECT FLUIDS AND SIGMA MODELS: A MATHEMATICAL INVESTIGATION BETWEEN GENERAL RELATIVITY AND COTTON GRAVITY
… The latter are special solutions of the Einstein field equations on a static space-time with matter sources modelled by a perfect fluid and a map φ, while the former are the natural generalization of φ-SPFSTs in the framework of a gravitational theory of recent introduction, called Cotton …
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Dynamical studies in relativistic cosmology
… in Relativistic Cosmology that is the Einstein Field Equations applied to the largest scales with source field typically taken to be a perfect fluid and fundamental observers comoving with the preferred fluid four-velocity. We show using a tetrad analysis of the evolution equations for …
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Colliding branes and formation of spacetime singularities in superstring theory.
A systematic study of space-times containing two timelike colliding branes is made, in the framework of 10-dimensional string theory. After developing the general formulas to describe such events, we study several classes of exact solutions and space-time singularities in both the (D+d)-dimensional …