Fixing the center-of-mass frame of numerical relativity waveforms using the post-Newtonian center-of-mass charge

Fuente: arXiv
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Main Authors: Khairnar, Aniket, Stein, Leo C., Boyle, Michael, Deppe, Nils, Kidder, Lawrence E., Mitman, Keefe, Moxon, Jordan, Nelli, Kyle C., Throwe, William, Vu, Nils L.
Format: Preprint
Published: 2026
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author Khairnar, Aniket
Stein, Leo C.
Boyle, Michael
Deppe, Nils
Kidder, Lawrence E.
Mitman, Keefe
Moxon, Jordan
Nelli, Kyle C.
Throwe, William
Vu, Nils L.
author_facet Khairnar, Aniket
Stein, Leo C.
Boyle, Michael
Deppe, Nils
Kidder, Lawrence E.
Mitman, Keefe
Moxon, Jordan
Nelli, Kyle C.
Throwe, William
Vu, Nils L.
contents The Bondi--van der Burg--Metzner--Sachs (BMS) frame of gravitational waves produced by numerical relativity (NR) simulations is crucial for building accurate waveform models. A proper comparison of NR waveforms with other models requires fixing the arbitrary BMS frame. In this work we improve the center-of-mass (CoM) frame fixing for quasicircular, nonprecessing binary systems. Past work approximated the CoM motion with just a linear fit. We compute a post-Newtonian result of the boosted CoM charge to also capture its physical out-spiraling oscillations. We show that using the analytical results improves the robustness of the fit parameters -- translation and boost vectors -- to the choice of duration and time of the fitting window. Our analysis demonstrates a maximum improvement in robustness when the window is placed at the center of the inspiral. We quantified this improvement by computing the ratio of variances of fit parameters when the fit window size is varied. The largest improvement in robustness of parameters is by a factor of $\sim 25$ for the boost vector and $\sim 20$ for the translation vector. Finally, we incorporate this method into the BMS frame-fixing routine of the python package $\texttt{scri}$ for waveforms produced with Cauchy-characteristic evolution.
format Preprint
id arxiv_https___arxiv_org_abs_2603_24661
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Fixing the center-of-mass frame of numerical relativity waveforms using the post-Newtonian center-of-mass charge
Khairnar, Aniket
Stein, Leo C.
Boyle, Michael
Deppe, Nils
Kidder, Lawrence E.
Mitman, Keefe
Moxon, Jordan
Nelli, Kyle C.
Throwe, William
Vu, Nils L.
General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
High Energy Physics - Theory
The Bondi--van der Burg--Metzner--Sachs (BMS) frame of gravitational waves produced by numerical relativity (NR) simulations is crucial for building accurate waveform models. A proper comparison of NR waveforms with other models requires fixing the arbitrary BMS frame. In this work we improve the center-of-mass (CoM) frame fixing for quasicircular, nonprecessing binary systems. Past work approximated the CoM motion with just a linear fit. We compute a post-Newtonian result of the boosted CoM charge to also capture its physical out-spiraling oscillations. We show that using the analytical results improves the robustness of the fit parameters -- translation and boost vectors -- to the choice of duration and time of the fitting window. Our analysis demonstrates a maximum improvement in robustness when the window is placed at the center of the inspiral. We quantified this improvement by computing the ratio of variances of fit parameters when the fit window size is varied. The largest improvement in robustness of parameters is by a factor of $\sim 25$ for the boost vector and $\sim 20$ for the translation vector. Finally, we incorporate this method into the BMS frame-fixing routine of the python package $\texttt{scri}$ for waveforms produced with Cauchy-characteristic evolution.
title Fixing the center-of-mass frame of numerical relativity waveforms using the post-Newtonian center-of-mass charge
topic General Relativity and Quantum Cosmology
High Energy Astrophysical Phenomena
High Energy Physics - Theory
url https://arxiv.org/abs/2603.24661