Improved outer boundary conditions for Einstein's field equations

	Special Guest Lectures
	Improved outer boundary conditions for Einstein's field equations
	Luisa T. Buchman, University of Texas at Austin
	Research Fellow
	Johnston Hall 338 May 03, 2007 - 12:15 pm
Abstract: Constructing absorbing outer boundary conditions in General Relativity is both a challenging problem and a timely one, as the need for accurate gravitational waveforms from numerical simulations of inspiralling and merging binary black holes becomes more critical. In this talk, I will present new boundary conditions for Einstein's field equations which are perfectly absorbing when contributions from curvature are taken into account, and which can be applied to fairly general foliations of spacetime by space-like hypersurfaces and general outer boundary shapes. In particular, I will present (1) a hierarchy of local boundary conditions C_L which is perfectly absorbing including first order in 2M/R curvature corrections for gravitational radiation up to a given angular momentum number L (where M is the mass of the spacetime and R is a typical radius of the outer boundary) and which significantly reduces spurious reflections due to backscatter, and (2) a non-local boundary condition D_2 which is exact when first order corrections in 2M/R for both curvature and backscatter are considered, for quadrupolar radiation. I will discuss the relative merits of these boundary conditions for binary black hole simulations.

Speaker's Bio: Born: Los Angeles, California Degrees: AB Harvard-Radcliffe College; PhD University of Washington (Advisor: James Bardeen) 2003 Recent appointments: NRC Research Associate, Jet Propulsion Laboratory 2004--06; Research Fellow, University of Texas at Austin 2006--07 Research interests: Numerical relativity: equation formulations, boundary conditions, initial data/ evolutions to future null infinity

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