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Light-Ring Stability for Ultracompact Objects Open
We prove the following theorem: axisymmetric, stationary solutions of the Einstein field equations formed from classical gravitational collapse of matter obeying the null energy condition, that are everywhere smooth and ultracompact (i.e.,…
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New definition of complexity for self-gravitating fluid distributions: The spherically symmetric, static case Open
We put forward a new definition of complexity, for static and spherically\nsymmetric self--gravitating systems, based on a quantity, hereafter referred to\nas complexity factor, that appears in the orthogonal splitting of the Riemann\ntens…
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Anisotropic compact stars in the Buchdahl model: A comprehensive study Open
In this article, we present a class of relativistic solutions describing spherically symmetric and static anisotropic stars in hydrostatic equilibrium. For this purpose, we consider a particularized matric potential, namely, Buchdahl ansat…
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Role of pressure anisotropy on relativistic compact stars Open
We investigate a compact spherically symmetric relativistic body with anisotropic particle pressure profiles. The distribution possesses characteristics relevant to modeling compact stars within the framework of general relativity. For thi…
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Spherical collapse of small masses in the ghost-free gravity Open
We discuss some properties of recently proposed models of a ghost-free gravity. For this purpose we study solutions of linearized gravitational equations in the framework of such a theory. We mainly focus on the version of the ghost-free t…
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Spherically symmetric charged compact stars Open
\n In this article we consider the static spherically symmetric metric of embedding class 1. When solving the Einstein–Maxwell field equations we take into account the presence of ordinary baryonic matter together with the electric charge.…
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A new model for spherically symmetric anisotropic compact star Open
\n In this article we obtain a new anisotropic solution for Einstein’s field equations of embedding class one metric. The solution represents realistic objects such as Her X-1 and RXJ 1856-37. We perform a detailed investigation of both ob…
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Effective theory of black holes in the 1/D expansion Open
The gravitational field of a black hole is strongly localized near its horizon when the number of dimensions D is very large. In this limit, we can effectively replace the black hole with a surface in a background geometry (eg Minkowski or…
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Minimal Geometric Deformation: the inverse problem Open
In this paper we show that any static and spherically symmetric anisotropic\nsolution of the Einstein field equations can be thought as a system sourced by\ncertain deformed isotropic system in the context of Minimal Geometric\nDeformation…
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A condition for a perfect-fluid space-time to be a generalized Robertson-Walker space-time Open
A perfect-fluid space-time of dimension n ≥ 4, with (1) irrotational velocity vector field and (2) null divergence of the Weyl tensor, is a generalised Robertson-Walker space-time with an Einstein fiber. Condition (1) is verified whenever …
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Asymptotics with a positive cosmological constant. III. The quadrupole formula Open
Almost a century ago, Einstein used a weak field approximation around\nMinkowski space-time to calculate the energy carried away by gravitational\nwaves emitted by a time changing mass-quadrupole. However, by now there is\nstrong observati…
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Exact barotropic distributions in Einstein-Gauss-Bonnet gravity Open
New exact solutions to the field equations in the Einstein--Gauss--Bonnet\nmodified theory of gravity for a 5--dimensional spherically symmetric static\ndistribution of a perfect fluid is obtained. The Frobenius method is used to\nobtain t…
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Thermodynamical first laws of black holes in quadratically-extended gravities Open
Einstein gravities in general dimensions coupled to a cosmological constant\nand extended with quadratic curvature invariants admit a variety of black holes\nthat may asymptote to Minkowski, anti-de Sitter or Lifshitz spacetimes. We\nadopt…
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Cosmological implications of modified gravity induced by quantum metric fluctuations Open
\n We investigate the cosmological implications of modified gravities induced by the quantum fluctuations of the gravitational metric. If the metric can be decomposed as the sum of the classical and of a fluctuating part, of quantum origin…
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Hydrodynamic representation of the Klein-Gordon-Einstein equations in the weak field limit: General formalism and perturbations analysis Open
Using a generalization of the Madelung transformation, we derive the\nhydrodynamic representation of the Klein-Gordon-Einstein equations in the weak\nfield limit. We consider a complex self-interacting scalar field with a\n$\\lambda|\\varp…
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A new class of relativistic model of compact stars of embedding class I Open
In the present paper, we have constructed a new relativistic anisotropic compact star model having a spherically symmetric metric of embedding class one. Here we have assumed an arbitrary form of metric function [Formula: see text] and sol…
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Gravitational Waves from Isolated Systems: Surprising Consequences of a Positive Cosmological Constant Open
There is a deep tension between the well-developed theory of gravitational waves from isolated systems and the presence of a positive cosmological constant Λ, however tiny. In particular a generalization of Einstein's 1918 quadrupole formu…
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Charged anisotropic strange stars in general relativity Open
\n The present paper provides a new exact and analytic solution of the Einstein–Maxwell field equations describing compact anisotropic charged stars satisfying the MIT bag model equation of state for quark matter. The model is obtained by …
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Spacetime dynamics of a Higgs vacuum instability during inflation Open
A remarkable prediction of the Standard Model is that, in the absence of corrections lifting the energy density, the Higgs potential becomes negative at large field values. If the Higgs field samples this part of the potential during infla…
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Some new Wyman–Leibovitz–Adler type static relativistic charged anisotropic fluid spheres compatible to self-bound stellar modeling Open
This article was published in the The European Physical Journal C [© The Author(s) 2015. This article is published with open access at Springerlink.com] and the definite version is available at : http://10.1140/epjc/s10052-015-3737-6 The J…
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Effective gravitational field equations on m-brane embedded in n-dimensional bulk of Einstein and $$f(\mathcal {R})$$ f ( R ) gravity Open
We have derived effective gravitational field equations on a lower\ndimensional hypersurface (known as a brane), placed in a higher dimensional\nbulk spacetime for both Einstein and $f(\\mathcal{R})$ gravity theories. We have\nstarted our …
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Gravitational field equations near an arbitrary null surface expressed as a thermodynamic identity Open
Previous work has demonstrated that the gravitational field equations in all\nLanczos-Lovelock models imply a thermodynamic identity TdS=dE+PdV (where the\nvariations are interpreted as changes due to virtual displacement along the\naffine…
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Radiation and Boundary Conditions in the Theory of Gravitation Open
The Sommerfeld boundary conditions, applied to an asymptotically weak gravitational field, are shown to imply that the 1/r part of the curvature tensor of a space-time, satisfying the Einstein equations, is of type null in the Petrov class…
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Possible physical realizations of the Tolman VII solution Open
The Tolman VII solution (an exact static spherically symmetric perfect fluid\nsolution) to the Einstein equations is reexamined, and a closed form equation\nof state (EOS) is deduced for the first time. This EOS allows further analysis\nle…
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A new unified theory of electromagnetic and gravitational interactions Open
In this paper we present a new unified theory of electromagnetic and gravitational interactions. By considering a four-dimensional spacetime as a hypersurface embedded in a five-dimensional bulk spacetime, we derive the complete set of fie…
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Dust Collapse in Asymptotic Safety: A Path to Regular Black Holes Open
Regular black hole spacetimes are obtained from an effective Lagrangian for quantum Einstein gravity. The interior matter is modeled as a dust fluid, which interacts with the geometry through a multiplicative coupling function denoted as χ…
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Relativistic numerical cosmology with silent universes Open
Relativistic numerical cosmology is most often based either on the exact solutions of the Einstein equations, or perturbation theory, or weak-field limit, or the BSSN formalism. The silent universe provides an alternative approach to inves…
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Buchdahl compactness limit for a pure Lovelock static fluid star Open
We obtain the Buchdahl compactness limit for a pure Lovelock static fluid star and verify that the limit following from the uniform density Schwarzschild's interior solution, which is universal irrespective of the gravitational theory (Ein…
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Stability analysis of Einstein universe in f(𝒢,T) gravity Open
This paper explores the stability of the Einstein universe against linear homogeneous perturbations in the background of [Formula: see text] gravity. We construct static as well as perturbed field equations and investigate stability region…
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Axially symmetric and static solutions of Einstein equations with self-gravitating scalar field Open
The exact axisymmetric and static solution of the Einstein equations coupled\nto axisymmetric and static gravitating scalar (or phantom) field is presented.\nThe spacetimes modified by the scalar field are explicitly given for the so\ncall…