The next generation of gravitational-wave observatories will achieve unprecedented strain sensitivities with an expanded observing band. They will detect O(105) binary neutron star (BNS) mergers every year, the loudest of which will be in the band for ≈90 minutes with signal-to-noise ratios ≈1500. Current techniques will not be able to determine the astrophysical parameters of the loudest of next-gen BNS signals. We show that subtleties arising from the rotation of the Earth and the free-spectral range of gravitational-wave interferometers dramatically increases the complexity of next-gen BNS signals compared to the one-minute signals seen by LIGO--Virgo. Various compression methods currently relied upon to speed up the most expensive BNS calculations -- reduced-order quadrature, multi-banding, and relative binning -- will no longer be effective. We carry out reduced-order inference on a simulated next-gen BNS signal taking into account the Earth's rotation and the observatories' free-spectral range. We show that standard data compression techniques become impractical, and the full problem becomes computationally infeasible, when we include data below ≈16Hz -- a part of the observing band that is critical for precise sky localisation. We discuss potential paths towards solving this complex problem.
@article{arxiv.2503.04073,
title = {Significant challenges for astrophysical inference with next-generation gravitational-wave observatories},
author = {A. Makai Baker and Paul D. Lasky and Eric Thrane and Jacob Golomb},
journal= {arXiv preprint arXiv:2503.04073},
year = {2025}
}