Determine exact PN–NR hybridization requirements to meet next-generation detector accuracies

Determine the precise requirements for hybridizing post-Newtonian and numerical-relativity waveforms to achieve the accuracy targets needed by next-generation gravitational-wave detectors, specifying conditions such as overlap regions, waveform lengths, and methodological criteria that ensure hybridizations are unbiased at the relevant signal-to-noise ratios.

Background

Next-generation observatories like Cosmic Explorer, Einstein Telescope, and LISA will require waveform models with substantially higher accuracy and longer duration than current catalogs typically provide. Because full NR coverage is computationally expensive, hybridization with post-Newtonian waveforms will be essential to span detector bands.

The authors explicitly note that the exact hybridization requirements—what constitutes sufficient overlap, how long the NR segments must be, and how to ensure unbiased analyses—have not yet been fully determined, making this a critical open question for future modeling efforts.