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In recent years, interest in extra dimensions has experienced a dramatic increase. A common practice has been to look for higher-dimensional generalizations of four-dimensional solutions to the Einstein equations. In this vein, we have…

General Relativity and Quantum Cosmology · Physics 2007-05-23 R. Steven Millward

This paper addresses the electromagnetic inverse scattering problem of determining the location and shape of anisotropic objects from near-field data. We investigate both cases involving the Helmholtz equation and Maxwell's equations for…

Numerical Analysis · Mathematics 2023-09-25 Tran H. Lan , Dinh-Liem Nguyen

The 'anholonomic frame' method (see gr-qc/0005025, gr-qc/0001060 and hep-th/0110250) is applied for constructing new classes of exact solutions of vacuum Einstein equations with off-diagonal metrics in 4D and 5D gravity. We examine several…

High Energy Physics - Theory · Physics 2007-05-23 Sergiu I. Vacaru

New theorems about the existence of solution for a system of infinite linear equations with a Vandermonde type matrix of coefficients are proved. Some examples and applications of these results are shown. In particular, a kind of these…

General Relativity and Quantum Cosmology · Physics 2015-06-17 J. L. Hernandez-Pastora

The paper deals with a special kind of problems that appear in solutions of Einstein's field equations for extended bodies: many structure-dependent terms appear in intermediate calculations that cancel exactly in virtue of the local…

General Relativity and Quantum Cosmology · Physics 2015-06-18 Sergei Klioner , Michael Soffel

We present a new formulation of Einstein's equations for an axisymmetric spacetime with vanishing twist in vacuum. We propose a fully constrained scheme and use spherical polar coordinates. A general problem for this choice is the…

General Relativity and Quantum Cosmology · Physics 2015-05-15 Christian Schell , Oliver Rinne

This paper constructs two immediate extensions of the existing anisotropic solutions in the context of Einstein-Maxwell framework by employing minimal geometric deformation. To achieve this, we assume a static spherical interior initially…

General Relativity and Quantum Cosmology · Physics 2023-10-03 M. Sharif , Tayyab Naseer

Recent works by the second author and Maxwell et al. have shown that the Einstein-scalar field conformal constraint equations are highly complex and generally intractable, even in the vacuum case. In this article, to gain a clearer…

General Relativity and Quantum Cosmology · Physics 2026-03-11 Philippe Castillon , Cang Nguyen-The

Using squeezed vacuum state formalism of quantum optics, an approximate solution to the semiclassical Einstein equation is obtained in Bianchi type-I universe. The phenomena of nonclassical particle creation is also examined in the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 P. K. Suresh

In this paper, we construct anisotropic spherical solutions from known isotropic solutions through extended gravitational decoupling method in the background of self-interacting Brans-Dicke theory. The field equations are decoupled into two…

General Relativity and Quantum Cosmology · Physics 2020-06-09 M. Sharif , Amal Majid

An exact solution of the Einstein field equations is proposed which represents a differentially rotating fluid. As this solution matches the exterior Kerr solution and reduces to the Schwarzschild interior solution by setting the rotational…

Astrophysics · Physics 2009-09-03 Rainer Burghardt

Recently, Khadekar (2007) presented the solutions with uniform energy density for anisotropic spheres in bimetric theory. We present here a general analytic solution to the field equations in bimetric theory for anisotropic fluids for a…

General Physics · Physics 2011-09-26 Naveen Bijalwan

There are a number of publications on relativistic objects dealing either with black holes or naked singularities in the center. Here we show that there exist static spherically symmetric solutions of Einstein equations with a strongly…

General Relativity and Quantum Cosmology · Physics 2024-08-27 O. S. Stashko , V. I. Zhdanov

The condition for pressure isotropy is reduced to a recurrence equation with variable, rational coefficients of order three. We prove that this difference equation can be solved in general. Consequently we can find an exact solution to the…

General Relativity and Quantum Cosmology · Physics 2009-11-11 A. J. John , S. D. Maharaj

With applications in astroparticle physics in mind, we generalize a method for the solution of the nonlinear, space homogeneous Boltzmann equation with isotropic distribution function to arbitrary matrix elements. The method is based on the…

Astrophysics · Physics 2009-11-06 A. Hohenegger

Ivanov pointed out substantial analytical difficulties associated with self-gravitating, static, isotropic fluid spheres when pressure explicitly depends on matter density. Simplification achieved with the introduction of electric charge…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Victor Varela , Farook Rahaman , Saibal Ray , Koushik Chakraborty , Mehedi Kalam

Motivated by studies on gravitational lenses, we present an exact solution of the field equations of general relativity, which is static and spherically symmetric, has no mass but has a non-vanishing spacelike components of the…

General Relativity and Quantum Cosmology · Physics 2012-03-15 Emanuel Gallo , Osvaldo Moreschi

Based upon the intrinsic symmetries approach to inhomogeneous cosmologies, we propose an exact solution to Einstein's field equations where the spatial sections are flat and the source is a non-perfect fluid such that the dissipative terms…

General Relativity and Quantum Cosmology · Physics 2021-03-11 E. Bittencourt , L. G. Gomes , G. B. Santos

We start with a recently introduced spherically symmetric geodesic fluid model (arXiv: 1601.07030) whose energy-momentum tensor in the comoving frame is dust-like with nontrivial energy flux. In the non-comoving energy frame (vanishing…

General Physics · Physics 2018-02-14 Peter C. Stichel

Einstein's equations are solved for spherically symmetric universes composed of dust with tangential pressure provided by angular momentum, L(R), which differs from shell to shell. The metric is given in terms of the shell label, R, and the…

General Relativity and Quantum Cosmology · Physics 2009-11-07 J. R. Gair