A5084067271- Black Holes and Theoretical Physics
- Cosmology and Gravitation Theories
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Relativity and Gravitational Theory
- Advanced Differential Geometry Research
- Geophysics and Gravity Measurements
- Advanced Mathematical Physics Problems
- Noncommutative and Quantum Gravity Theories
- Electromagnetic Simulation and Numerical Methods
- Model Reduction and Neural Networks
- Radio Astronomy Observations and Technology
- Algebraic and Geometric Analysis
- Quantum and Classical Electrodynamics
- Numerical methods in inverse problems
- Geophysics and Sensor Technology
- Numerical methods for differential equations
- Statistical and numerical algorithms
- Mathematics and Applications
- Experimental and Theoretical Physics Studies
- advanced mathematical theories
- Particle physics theoretical and experimental studies
- Scientific Research and Discoveries
- Electromagnetic Scattering and Analysis
- Geotechnical and Geomechanical Engineering
University of Pittsburgh
2009-2024
Max Planck Institute for Gravitational Physics
2009-2019
Pittsburg State University
2018
Max Planck Society
2000-2017
University of South Africa
1996-1997
Max Planck Institute for Physics
1987
Max Planck Institute for Astrophysics
1987
U.S. National Science Foundation
1984
Illinois Institute of Technology
1973
Wright-Patterson Air Force Base
1965-1972
A spherically symmetric solution of the Einstein equations is presented that coincides with exterior ($\mathcal{r}>2m$) Schwarzschild solution, but where "sphere" becomes a point singularity. The possible relevance this to question gravitational collapse discussed.
We generalize the Bondi-Sachs treatment of initial-value problem using null coordinate systems. This is applicable in both finite and asymptotic regions space whose sources are bounded by a world tube. Using conformal techniques developed Penrose, we rederive results Bondi co-workers Sachs conformal-space language. Definitions symmetry "linkages" which offer an invariant way labeling properties space, e.g., energy momentum. These linkages form representation Bondi-Metzner-Sachs group.
The Bondi-Sachs formalism of General Relativity is a metric-based treatment the Einstein equations in which coordinates are adapted to null geodesics spacetime.It provided first convincing evidence that gravitational radiation nonlinear effect general relativity and emission waves from an isolated system accompanied by mass loss system.The asymptotic behaviour metric revealed existence symmetry group at infinity, Bondi-Metzner-Sachs group, turned out be larger than Poincare group.Contents 1...
We describe the computation of Bondi news for gravitational radiation. have implemented a computer code this problem. discuss theory behind it as well results validation tests. Our approach uses compactified null cone formalism, with computational domain extending to future infinity and world tube inner boundary. calculate appropriate full Einstein equations in $e$th form (a) interior (b) on At infinity, we transform computed data into standard coordinates so are able express terms its...
We treat the calculation of gravitational radiation using mixed timelike-null initial value formulation general relativity. The determination an exterior radiative solution is based on boundary values a timelike world tube $\ensuremath{\Gamma}$ and characteristic data outgoing null cone emanating from cross section $\ensuremath{\Gamma}$. present details three-dimensional computational algorithm which evolves this numerical grid, compactified to include future infinity as finite grid points....
The Binary Black Hole Alliance was formed to study the collision of black holes and resulting gravitational radiation by computationally solving Einstein's equations for general relativity. location hole surface in a head-on has been determined detail is described here. geometrical features that emerge are presented along with an analysis explanation terms spacetime curvature inherent strongly gravitating region. This plays direct, important, analytically explicable role formation evolution...
For an asymptotically flat space–time in general relativity there exist certain integrals, called linkages, over cross sections of null infinity, which represent the energy, momentum, or angular momentum system. A new formulation linkages is introduced and applied. It shown that exists a flux, representing contribution gravitational matter radiation to linkage. uniqueness conjecture for formulated. The ambiguities due possible presence supertranslations asymptotic rotations are studied using...
The production of gravitational waves is explored, both analytically and numerically, using a null cone formulation axially symmetric matter fields. coupled field equations are written in an integral form, on single conformally compactified patch, which well suited for numerical computation. Some analytic solutions the initial value problem given. total mass radiation flux studied detail special class collapsing dust configurations.
Simple solutions of the Einstein scalar and Brans-Dicke field equations are exhibited, nature Killing horizons some static is discussed.Received 15 April 1969DOI:https://doi.org/10.1103/PhysRev.186.1729©1969 American Physical Society
Binary black-hole interactions provide potentially the strongest source of gravitational radiation for detectors currently under development. We present some results from Black Hole Grand Challenge Alliance three-dimensional Cauchy evolution module. These constitute essential steps towards modeling such and predicting waveforms. report on single evolutions first successful demonstration a black hole moving freely through computational grid via evolution: near 6M at 0.1c during total duration...
Maximally dissipative boundary conditions are applied to the initial-boundary value problem for Einstein's equations in harmonic coordinates show that it is well posed homogeneous data and small a linearized sense. The method implemented as nonlinear evolution code, which satisfies convergence tests regime stable weak field regime. A version has been stably matched characteristic code compute gravitational wave form radiated infinity.
We present a method for extracting gravitational radiation from three-dimensional numerical relativity simulation and, using the extracted data, to provide outer boundary conditions. The treats dynamical variables as nonspherical perturbations of Schwarzschild geometry. discuss code which implements this and results tests have been performed with code.Received 29 September 1997DOI:https://doi.org/10.1103/PhysRevLett.80.1812©1998 American Physical Society
We present the first simulations of non-head-on (grazing) collisions binary black holes in which singularities are excised from simulation. Initially equal mass $m$ (spinning or not) separated by $\ensuremath{\approx}10m$ and with impact parameter $\ensuremath{\approx}2m$. Evolutions to $t\ensuremath{\approx}35m$ obtained where two separate horizons for $t\ensuremath{\approx}3.8m$; then a single enveloping horizon forms indicating that merged. Apparent area estimates suggest gravitational...
We develop and calibrate a characteristic waveform extraction tool whose major improvements corrections of prior versions allow satisfaction the accuracy standards required for advanced LIGO data analysis. The uses evolution code to propagate numerical on an inner worldtube supplied by 3+1 Cauchy obtain gravitational at null infinity. With new tool, high convergence error can be demonstrated inspiral merger mass M binary black holes even radius as small R = 20M. provides means unambiguous...
Properties of event horizons are examined for static, axially symmetric, vacuum space-times. Israel has shown that under fairly general conditions such singular. One would expect a positive-mass point particle correspond to pointlike singular horizon. It is shown, however, the cannot be pointlike. The geometry particular discussed.
The total energy, momentum, supermomentum, and angular momentum of asymptotically flat space-times are calculated in terms coordinate conformally invariant expressions by taking the limit an way asymptotic symmetry linkages through a sequence finite closed two-spaces which converge to sphere at null infinity. resulting consist integrals over infinity cordinate quantities. In case energy these may be reduced previously proposed Penrose.
Gravitational radiation has a memory effect represented by net change in the relative positions of test particles. Both linear and nonlinear sources proposed for this are 'electric' type, or E mode, as characterized even parity polarization pattern. Although 'magnetic' B is mathematically possible, no physically realistic source been identified. There an electromagnetic counterpart to which velocity charged particles obtain 'kick'. Again, that have identified electric type. In paper, global...
In recent years, many different numerical evolution schemes for Einstein's equations have been proposed to address stability and accuracy problems that plagued the relativity community decades. Some of these approaches tested on spacetimes, conclusions drawn based tests. However, differences in results originate from sources, including not only formulations equations, but also gauges, boundary conditions, methods so on. We propose build up a suite standardized testbeds comparing are designed...
We report new results which establish that the accurate three-dimensional numerical simulation of generic single-black-hole spacetimes has been achieved by characteristic evolution with unlimited long term stability. Our include distorted, moving, and spinning single black holes, times up to 60000M.Received 12 January 1998DOI:https://doi.org/10.1103/PhysRevLett.80.3915©1998 American Physical Society
For a general relativistic ideal fluid, we analyze the Newtonian limit of initial value problem set on family null cones. The underlying structure is described using Cartan’s elegant space–time version theory and limiting process rigorously based upon velocity light approaching infinity. We find that existence imposes strikingly simple relationship between gravitational data (i.e., shear cones) potential. This result has immediate application to numerical evolution programs for calculating...
We investigate the initial-boundary value problem for linearized gravitational theory in harmonic coordinates. Rigorous techniques hyperbolic systems are applied to establish well posedness various reductions of system into a set six wave equations. The results used formulate computational algorithms Cauchy evolution 3-dimensional bounded domain. Numerical codes based upon these shown satisfy tests robust stability random constraint violating initial data and boundary data, give excellent...
We study the properties of outgoing gravitational wave produced when a non-spinning black hole is excited by an ingoing wave. Simulations using numerical code for solving Einstein's equations allow to be extended from linearized approximation, where system treated as perturbed Schwarzschild hole, fully nonlinear regime. Several features are found which bear importance data analysis waves. When compared results obtained in we observe large phase shifts, stronger than linear generation output...
Recent theorems regarding topological censorship are in apparent conflict with simulations of the collapse rotating matter to form toroidal black holes. The geometry a temporarily event horizon is analyzed and shown be completely consistent theorems. A simple flat space model provides insight into hole. \textcopyright{} 1995 American Physical Society.