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Published October 22, 2013 | Published + Submitted
Journal Article Open

Joint approach for reducing eccentricity and spurious gravitational radiation in binary black hole initial data construction

Abstract

At the beginning of binary black hole simulations, there is a pulse of spurious radiation (or junk radiation) resulting from the initial data not matching astrophysical quasi-equilibrium inspiral exactly. One traditionally waits for the junk radiation to exit the computational domain before taking physical readings, at the expense of throwing away a segment of the evolution, and with the hope that junk radiation exits cleanly. We argue that this hope does not necessarily pan out, as junk radiation could excite long-lived constraint violation. Another complication with the initial data is that they contain orbital eccentricity that needs to be removed, usually by evolving the early part of the inspiral multiple times with gradually improved input parameters. We show that this procedure is also adversely impacted by junk radiation. In this paper, we do not attempt to eliminate junk radiation directly, but instead tackle the much simpler problem of ameliorating its long-lasting effects. We report on the success of a method that achieves this goal by combining the removal of junk radiation and eccentricity into a single procedure. Namely, we periodically stop a low resolution simulation; take the numerically evolved metric data and overlay it with eccentricity adjustments; run it through an initial data solver (i.e. the solver receives as free data the numerical output of the previous iteration); restart the simulation; repeat until eccentricity becomes sufficiently low; and then launch the high resolution "production run" simulation. This approach has the following benefits: (1) We do not have to contend with the influence of junk radiation on eccentricity measurements for later iterations of the eccentricity reduction procedure. (2) We reenforce constraints every time the initial data solver is invoked, removing the constraint violation excited by junk radiation previously. (3) The wasted simulation segment associated with the junk radiation's evolution is absorbed into the eccentricity reduction iterations. Furthermore, (1) and (2) together allow us to carry out our joint-elimination procedure at low resolution, even when the subsequent "production run" is intended as a high resolution simulation.

Additional Information

© 2013 American Physical Society. Received 4 September 2013; published 22 October 2013. We would like to thank Nicholas Taylor and Mark Scheel for helpful discussions, and Harald Pfeiffer, William Throwe, Saul Teukolsky and Daniel Hemberger for reading a draft of the paper and providing valuable comments. This research is supported by NSF Grants No. PHY-1068881 and No. PHY-1005655, NASA Grants No. NNX09AF97G and No. NNX09AF96G, and by the Sherman Fairchild Foundation and the Brinson Foundation. The numerical work was carried out on the Caltech computer cluster ZWICKY, funded by the Sherman Fairchild Foundation and the NSF MRI-R2 Grant No. PHY-0960291.

Attached Files

Published - PhysRevD.88.084033.pdf

Submitted - 1309.1141v1.pdf

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August 19, 2023
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October 25, 2023