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Computational Science Seminar Announcement
|Date & Time:||
Tuesday , 04/16/2013
from 03:30 PM to 04:30 PM
|Location:||LArts Room 218|
|Sponsored by:||NSF and Provost's seminar series|
Title: "Fast recovery of far-field signals from gravitational perturbations"
Time-domain simulation of blackhole perturbations on a finite computational domain requires the introduction of a fictitious outer boundary. On this surface we seek to i) supply exact radiation boundary conditions and ii) recover the asymptotic (far-field) signal which would reach large distances including infinity. Far-field signals are especially important as they encode information about the physical system. In this talk I show how both radiation boundary conditions and signal recovery are easily handled via a time-domain convolution of the solution recorded at the outer boundary with a small number of damped exponentials. In turn, each exponentials' strength and damping rate arises from a sum-of-poles approximation of a Laplace frequency domain kernel. I will motivate the origin of the frequency domain kernel by analogy to the ordinary 3+1 wave equation as well as the numerical techniques needed for its sum-of-poles approximation. The technique is used to study late-time decay tails at infinity, "teleportation" of a signal between two finite radial values and signals from binary black hole systems.