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We present a novel homogeneous and geometrically flat exact solution of Einstein's General Relativity equations for an ideal fluid. The solution, which describes an expanding/contracting hypercylinder, fits well with the observational…

Cosmology and Nongalactic Astrophysics · Physics 2010-10-05 David H. Oaknin

In this paper, we present a formalism to generate a family of interior solutions to the Einstein-Maxwell system of equations for a spherically symmetric relativistic charged fluid sphere matched to the exterior Reissner-Nordstr\"om…

General Physics · Physics 2018-05-09 K. Komathiraj , Ranjan Sharma

We consider a system representing self-gravitating balls of dust in an expanding Universe. It is demonstrated that one can prescribe data for such a system at infinity and evolve it backward in time without the development of shocks or…

General Relativity and Quantum Cosmology · Physics 2022-06-29 Shabnam Beheshti , Mikael Normann , Juan Valiente Kroon

A new simulation method for solving fluid-structure coupling problems has been developed. All the basic equations are numerically solved on a fixed Cartesian grid using a finite difference scheme. A volume-of-fluid formulation (Hirt and…

Computational Physics · Physics 2015-05-20 Kazuyasu Sugiyama , Satoshi Ii , Shintaro Takeuchi , Shu Takagi , Yoichiro Matsumoto

We describe the special relativistic extension of the CRONOS code, which has been used for studies of gamma-ray binaries in recent years. The code was designed to be easily adaptable, allowing the user to easily change existing…

High Energy Astrophysical Phenomena · Physics 2021-09-29 David Huber , Ralf Kissmann

We study the evolution of an anisotropic shear-free fluid with heat flux and kinematic self-similarity of the second kind. We found a class of solution to the Einstein field equations by assuming that the part of the tangential pressure…

General Relativity and Quantum Cosmology · Physics 2014-05-13 R. Chan , M. F. A. da Silva , C. F. C. Brandt

In this paper we consider singular timelike spherical hypersurfaces embedded in a $D$-dimensional spherically symmetric bulk spacetime which is an electrovacuum solution of Einstein equations with cosmological constant. We analyse the…

General Relativity and Quantum Cosmology · Physics 2019-03-19 Marcos A. Ramirez , Daniel Aparicio

Novel applications of Numerical Relativity demand for more flexible algorithms and tools. In this paper, I develop and test a multigrid solver, based on the infrastructure provided by the Einstein Toolkit, for elliptic partial differential…

General Relativity and Quantum Cosmology · Physics 2015-06-16 Eloisa Bentivegna

Many systems of current interest in relativistic astrophysics require a knowledge of radiative transfer in a magnetized gas flowing in a strongly-curved, dynamical spacetime. Such systems include coalescing compact binaries containing…

Astrophysics · Physics 2008-11-26 Brian D. Farris , Tsz Ka Li , Yuk Tung Liu , Stuart L. Shapiro

A method is introduced for solving Einstein's equations using two distinct coordinate systems. The coordinate basis vectors associated with one system are used to project out components of the metric and other fields, in analogy with the…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Mark A. Scheel , Harald P. Pfeiffer , Lee Lindblom , Lawrence E. Kidder , Oliver Rinne , Saul A. Teukolsky

This is a short review of a series of papers which, in collaboration with Yue Ma, establish several novel existence results for systems of coupled wave-Klein-Gordon equation. Our method, the Hyperbolic Hyperboloidal Method, has allowed us…

Analysis of PDEs · Mathematics 2017-01-02 Philippe G. LeFloch

Analogue gravity offers an approach for testing the universality and robustness of quantum field theories in curved spacetimes and validating them using down-to-earth, laboratory-based experiments. Fluid interfaces are a promising framework…

General Relativity and Quantum Cosmology · Physics 2023-06-27 Vitor S. Barroso , Cameron R. D. Bunney , Silke Weinfurtner

We investigate the possibility to approximate relativistic effects in hydrodynamical simulations of stellar core collapse and post-bounce evolution by using a modified gravitational potential in an otherwise standard Newtonian hydrodynamic…

Astrophysics · Physics 2009-11-10 A. Marek , H. Dimmelmeier , H. -Th. Janka , E. Mueller , R. Buras

We study the solutions of the semiclassical Einstein equation in flat cosmological spacetimes driven by a massive conformally coupled scalar field. In particular, we show that it is possible to give initial conditions at finite time to get…

Mathematical Physics · Physics 2015-03-10 Nicola Pinamonti , Daniel Siemssen

Assuming conformally flat metric we obtain inhomogeneous solutions of Einstein equations with the energy-momentum of a viscous fluid. We suggest that the viscous solution can be applied as a model of an expanding inhomogeneous dark energy.

General Relativity and Quantum Cosmology · Physics 2020-03-31 Z. Haba

This is an important and natural question as the spacetime shear, inhomogeneity and tidal effects are all intertwined via the Einstein field equations. However, as we show in this paper, such scenarios are possible for limited classes of…

General Relativity and Quantum Cosmology · Physics 2024-06-18 Jonathan Hakata , Rituparno Goswami , Chevarra Hansraj , Sunil D. Maharaj

For the evolution of a compressible fluid in spherical symmetry on a Schwarzschild curved background, we design a class of well-balanced numerical algorithms with first-order or second-order of accuracy. We treat both the relativistic…

Numerical Analysis · Mathematics 2021-04-27 Philippe G. LeFloch , Carlos Parés , Ernesto Pimentel-García

Following a solution generating technique introduced recently by one of us, we transform the Einstein static Universe into a two - fold infinity class of physically acceptable exact perfect fluid solutions of Einstein's equations. Whereas…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Cédric Grenon , Pascal J. Elahi , Kayll Lake

We introduce a proposal to modify Einstein's equations by embedding them in a larger symmetric hyperbolic system. The additional dynamical variables of the modified system are essentially first integrals of the original constraints. The…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Othmar Brodbeck , Simonetta Frittelli , Peter Huebner , Oscar A. Reula

We describe in this article a new code for evolving axisymmetric isolated systems in general relativity. Such systems are described by asymptotically flat space-times which have the property that they admit a conformal extension. We are…

General Relativity and Quantum Cosmology · Physics 2009-11-07 J. Frauendiener , Matthias Hein