TY - JOUR

T1 - Inconsistent black hole kick estimates from gravitational-wave models

AU - Borchers, Angela

AU - Ohme, Frank

N1 - Funding Information: This work was supported by the Max Planck Society’s Independent Research Group program. Computations were carried out on the Holodeck cluster of the Max Planck Institute for Gravitational Physics in Hannover.

PY - 2023/5/4

Y1 - 2023/5/4

N2 - The accuracy of gravitational-wave (GW) models of compact binaries has traditionally been addressed by the mismatch between the model and numerical-relativity (NR) simulations. This is a measure of the overall agreement between the two waveforms. However, the largest modelling error typically appears in the strong-field merger regime and may affect subdominant signal harmonics more strongly. These inaccuracies are often not well characterised by the mismatch. We explore the use of a complementary, physically motivated tool to investigate the accuracy of GW harmonics in waveform models: the remnant’s recoil, or kick velocity. Asymmetric binary mergers produce remnants with significant recoil, encoded by subtle imprints in the GW signal. The kick estimate is highly sensitive to the intrinsic inaccuracies of the modelled GW harmonics during the strongly relativistic merger regime. Here we investigate the accuracy of the higher harmonics in four state-of-the-art waveform models of binary black holes. We find that the SEOBNRv4HM_ROM, IMRPhenomHM, IMRPhenomXHM and NRHybSur3dq8 models are not consistent in their kick predictions. Our results enable us to identify regions in the parameter space where the models require further improvement and support the use of the kick estimate to investigate waveform systematics. We discuss how NR kick estimates could be used to calibrate waveform models further, proposing the first steps towards kick-based gravitational-wave tuning.

AB - The accuracy of gravitational-wave (GW) models of compact binaries has traditionally been addressed by the mismatch between the model and numerical-relativity (NR) simulations. This is a measure of the overall agreement between the two waveforms. However, the largest modelling error typically appears in the strong-field merger regime and may affect subdominant signal harmonics more strongly. These inaccuracies are often not well characterised by the mismatch. We explore the use of a complementary, physically motivated tool to investigate the accuracy of GW harmonics in waveform models: the remnant’s recoil, or kick velocity. Asymmetric binary mergers produce remnants with significant recoil, encoded by subtle imprints in the GW signal. The kick estimate is highly sensitive to the intrinsic inaccuracies of the modelled GW harmonics during the strongly relativistic merger regime. Here we investigate the accuracy of the higher harmonics in four state-of-the-art waveform models of binary black holes. We find that the SEOBNRv4HM_ROM, IMRPhenomHM, IMRPhenomXHM and NRHybSur3dq8 models are not consistent in their kick predictions. Our results enable us to identify regions in the parameter space where the models require further improvement and support the use of the kick estimate to investigate waveform systematics. We discuss how NR kick estimates could be used to calibrate waveform models further, proposing the first steps towards kick-based gravitational-wave tuning.

KW - black-hole remnant kicks

KW - gravitational waveform models

KW - waveform systematics

UR - http://www.scopus.com/inward/record.url?scp=85152211476&partnerID=8YFLogxK

U2 - 10.48550/arXiv.2207.13531

DO - 10.48550/arXiv.2207.13531

M3 - Article

AN - SCOPUS:85152211476

VL - 40

JO - Classical and quantum gravity

JF - Classical and quantum gravity

SN - 0264-9381

IS - 9

M1 - 095008

ER -