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Numerical studies of the dynamics of gravitational systems, e.g., black hole-neutron star systems, require physical and constraint-satisfying initial data. In this article, we present the newly developed pseudo-spectral code Elliptica, an…

General Relativity and Quantum Cosmology · Physics 2022-05-25 Alireza Rashti , Francesco Maria Fabbri , Bernd Brügmann , Swami Vivekanandji Chaurasia , Tim Dietrich , Maximiliano Ujevic , Wolfgang Tichy

We describe a method for initializing characteristic evolutions of the Einstein equations using a linearized solution corresponding to purely outgoing radiation. This allows for a more consistent application of the characteristic (null…

General Relativity and Quantum Cosmology · Physics 2015-03-18 Nigel Bishop , Denis Pollney , Christian Reisswig

General relativity can describe various gravitational systems of astrophysical relevance, like black holes and neutron stars, or even strongly coupled systems through the holographic duality. The characteristic initial (boundary) value…

General Relativity and Quantum Cosmology · Physics 2023-08-31 Thanasis Giannakopoulos

In this paper, we consider the initial value problem for the Einstein-Vlasov-Scalar field equations in temporal gauge, where the initial data are prescribed on two characteristic smooth intersecting hypersurfaces. From a suitable choice of…

Mathematical Physics · Physics 2016-08-04 Marcel Dossa , Jean Baptiste Patenou

The initial value problem is well-defined on a class of spacetimes broader than the globally hyperbolic geometries for which existence and uniqueness theorems are traditionally proved. Simple examples are the time-nonorientable spacetimes…

General Relativity and Quantum Cosmology · Physics 2007-05-23 John L. Friedman

We present an alternative approach to setting initial data in general relativity. We do not use a conformal decomposition, but instead express the 3-metric in terms of a given unit vector field and one unknown scalar field. In the case of…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Nigel T. Bishop , Florian Beyer , Michael Koppitz

We consider the initial data problem for several black holes in vacuum with arbitrary momenta and spins on a three space with punctures. We compactify the internal asymptotically flat regions to obtain a computational domain without inner…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Steven Brandt , Bernd Bruegmann

We revisit Winicour's affine-null metric initial value formulation of General Relativity, where the characteristic initial value formulation is set up with a null metric having two affine parameters. In comparison to past work, where the…

General Relativity and Quantum Cosmology · Physics 2019-05-24 Thomas Mädler

We present an approximate metric for a binary black hole spacetime to construct initial data for numerical relativity. This metric is obtained by asymptotically matching a post-Newtonian metric for a binary system to a perturbed…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Nicolas Yunes , Wolfgang Tichy , Benjamin J. Owen , Bernd Bruegmann

A classical problem in general relativity is the Cauchy problem for the linearised Einstein equation (the initial value problem for gravitational waves) on a globally hyperbolic vacuum spacetime. A well-known result is that it is uniquely…

Differential Geometry · Mathematics 2020-01-08 Oliver Lindblad Petersen

A method is presented to construct initial data for Einstein's equations as a superposition of a gravitational wave perturbation on an arbitrary stationary background spacetime. The method combines the conformal thin sandwich formalism with…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Harald P. Pfeiffer , Lawrence E. Kidder , Mark A. Scheel , Deirdre Shoemaker

The standard approach to initial data for both analytic and numerical computations of black hole collisions has been to use conformally-flat initial geometry. Among other advantages, this choice allows the simple superposition of holes with…

General Relativity and Quantum Cosmology · Physics 2009-10-31 W. Krivan , R. H. Price

We investigate the initial value problem for the Einstein-Euler equations of general relativity under the assumption of Gowdy symmetry on T3, and we construct matter spacetimes with low regularity. These spacetimes admit, both, impulsive…

General Relativity and Quantum Cosmology · Physics 2015-05-18 Philippe G. LeFloch , Alan D. Rendall

We present a multi-domain spectral method to compute initial data of binary systems in General Relativity. By utilizing adapted conformal coordinates, the vacuum region exterior to the gravitational sources is divided up into two subdomains…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Marcus Ansorg

In many numerical implementations of the Cauchy formulation of Einstein's field equations one encounters artificial boundaries which raises the issue of specifying boundary conditions. Such conditions have to be chosen carefully. In…

General Relativity and Quantum Cosmology · Physics 2010-09-06 Oscar Reula , Olivier Sarbach

We make use of an improved existence result for the characteristic initial value problem for the conformal Einstein equations to show that given initial data on two null hypersurfaces $\mathcal{N}_\star$ and $\mathcal{N}'_\star$ such that…

General Relativity and Quantum Cosmology · Physics 2024-06-19 Peng Zhao , David Hilditch , Juan A. Valiente Kroon

We consider the Einstein-Maxwell system as a Cauchy initial value problem taking the electric and magnetic fields as independent variables. Maxwell's equations in curved spacetimes are derived in detail using a 3+1 formalism and their…

General Relativity and Quantum Cosmology · Physics 2009-11-29 Miguel Alcubierre , Juan Carlos Degollado , Marcelo Salgado

This is the first in a series of articles on the numerical solution of Friedrich's conformal field equations for Einstein's theory of gravity. We will discuss in this paper why one should be interested in applying the conformal method to…

General Relativity and Quantum Cosmology · Physics 2016-08-25 J. Frauendiener

We study here the spherical gravitational collapse assuming initial data to be necessarily smooth, as motivated by the requirements based on physical reasonableness. A tangential pressure model is constructed and analyzed in order to…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Ashutosh Mahajan , Rituparno Goswami , Pankaj S. Joshi

For a class of scalar fields including the massless Klein-Gordon field the general relativistic hyperboloidal initial value problems are equivalent in a certain sense. By using this equivalence and conformal techniques it is proven that the…

General Relativity and Quantum Cosmology · Physics 2009-10-22 Peter Huebner