About gravitational-wave generation by a three-body system

Understand

We highlight some subtleties that affect naive implementations of quadrupolar and octupolar gravitational waveforms from numerically-integrated trajectories of three-body systems.

• Some of those subtleties arise from the requirement that the source be contained in its "coordinate near zone" when applying the standard PN formulae for gravitational-wave emission, and from the need to use the non-linear Einstein equations to correctly derive the quadrupole emission formula.
• We show that some of these subtleties were occasionally overlooked in the literature, with consequences for published results.
• We also provide prescriptions that lead to correct and robust predictions for the waveforms computed from numerically-integrated orbits.