# Characteristic Evolution and Matching

**Jeffrey Winicour
**

Max Planck Institute for Gravitational Physics

(Albert Einstein Institute)

Am Mühlenberg 1

14476 Potsdam-Golm, Germany

and

Department of Physics and Astronomy

University of Pittsburgh

Pittsburgh, PA 15260, U.S.A.

http://www.phyast.pitt.edu/people/fprofile.php?id=191

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Abstract

I review the development of numerical evolution codes for general relativity based upon the
characteristic initial value problem. Progress is traced from the early stage of 1D feasibility
studies to 2D axisymmetric codes that accurately simulate the oscillations and gravitational
collapse of relativistic stars and to current 3D codes that provide pieces of a binary black
hole spacetime. Cauchy codes have now been successful at simulating all aspects of the binary
black hole problem inside an artificially constructed outer boundary. A prime application
of characteristic evolution is to eliminate the role of this artificial outer boundary via
Cauchy-characteristic matching, by which the radiated waveform can be computed at null
infinity. Progress in this direction is discussed.