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Using openGR for numerical relativityWalter, Paul Joseph, 1978- 11 February 2011 (has links)
Binary black hole mergers are the strongest expected producers of graviational
radiation in the universe. Ground-based and proposed space-based
gravitational wave detectors will benefit from simulations modeling the mergers
and extracting the resulting gravitational waveforms. Producing templates
of waveforms will both aid the likelihood of detection and the estimation of
parameters (mass ratio, spin, etc.). openGR is modular, open framework development
to carry out simulations of binary black hole mergers. While designed
with the two-body problem in mind, openGR will evolve most general
spacetimes.
This work overviews the capabilities of openGR and the corresponding physics involved. openGR supports both excision and puncture methods.
When excising the black hole, to date we have used only the weakly hyperbolic
ADM formulation of the Einstein’s equations. As expected from a weakly hyperbolic
system, instabilites arise and crash the code when simulating even just
a single boosted black hole in Kerr-Schild coordinates. In contrast, successful
mergers of two black holes have been achieved using the puncture method. We
demonstrate such a simulation in Ch 8. In this case, we make use of a BSSN
formulation of Einstein’s equations (a strongly hyperbolic system). / text
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Computing binary black hole merger waveforms using openGRMcIvor, Greg Andrew 17 July 2012 (has links)
One of the most important predictions of General Relativity, Einstein’s
theory of gravity, is the existence of gravitational radiation. The strongest
source of such radiation is expected to come from the merging of black holes.
Upgrades to large ground based interferometric detectors (LIGO, VIRGO,
GEO 600) have increased their sensitivity to the point that the first direct
observation of a gravitational wave is expected to occur within the next few
years. The chance of detection is greatly improved by the use of simulated
waveforms which can be used as templates for signal processing. Recent advances
in numerical relativity have allowed for long stable evolution of black
hole mergers and the generation of expected waveforms.
openGR is a modular, open framework black hole evolution code developed
at The University of Texas at Austin Center for Relativity. Based on the
BSSN (strongly hyperbolic) formulation of Einstein’s equations and the moving
puncture method, we are able to model the evolution of a binary black hole
system through the merger and extract the gravitational radiation produced.
Although we are generally interested in binary interactions, openGR is capable
of handling any number of black holes. This work serves as an overview of the
capabilities of openGR and a demonstration of the physics it can be used to
explore. / text
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