Datensatz

Zusammenfassung

Gravitational-wave observations of binary black holes currently rely on theoretical models that predict the dominant multipole radiation during the coalescence. Here we introduce a simple method to include the subdominant multipole contributions to binary black hole gravitational waveforms, given a frequency-domain model for the dominant $(\ell=2,|m|=2)$ multipoles. The amplitude and phase of the original model are appropriately stretched and rescaled using leading-order post-Newtonian results (for the inspiral), perturbation theory (for the ringdown), and a smooth transition between the two. No additional tuning to numerical-relativity simulations is required. We apply a variant of this method to the non-precessing PhenomD model. The result, PhenomHM, constitutes the first higher-multipole model of spinning black-hole binaries, and currently includes $(\ell,|m|) = (2,2), (3,3), (4,4), (2,1), (3,2), (4,3)$. Comparisons with a set of numerical-relativity waveforms demonstrate that PhenomHM is more accurate than PhenomD for all binary configurations, and using PhenomHM typically leads to improved measurements of the binary's properties. Our approach can be extended to precessing systems, enabling wide-ranging studies of the impact of higher harmonics on gravitational-wave astronomy, and tests of fundamental physics.