Measuring spin precession from massive black hole binaries with gravitational waves: Insights from time-domain signal morphology
Creators
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1.
California Institute of Technology
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2.
Laser Interferometer Gravitational Wave Observatory
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3.
Flatiron Institute
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4.
University of Massachusetts Dartmouth
Abstract
Robustly measuring binary black hole spins via gravitational waves is key to understanding these systems’ astrophysical origins, but remains challenging—especially for high-mass systems, whose signals are short and dominated by the merger. Nonetheless, events like GW190521 show that strong spin precession can indeed be gleaned from high-mass systems. In this work, we track how spin precession imprints on simulated high-mass binary black hole signals cycle-by-cycle using time-domain inference. We investigate a suite of signals, all with the same spins and (near-unity) mass ratio—yielding identical spin evolution—but different signal-to-noise ratios, total masses, and extrinsic angles, all of which affect the observed waveform morphology. We truncate each signal at various times and infer source parameters using only the data before or after each cutoff. The resultant posterior allows us to identify which time segments of each signal inform its spin precession constraints. We find that at a sufficiently high post-peak signal-to-noise ratio (SNR, 𝜌 ∼20), spin precession can be constrained by the nrsur7dq4 waveform model when just the post-peak data (i.e., ringdown) are visible. Similarly, at a large enough pre-cutoff SNR (𝜌 ∼10), spin precession can be constrained using only pre-peak data (i.e., inspiral)—this occurs for signals with detector-frame total mass ≲100𝑀⊙ at GW190521’s full-signal SNR. Finally, we vary the inclination, polarization, and phase angles, finding that their configuration need not be fine-tuned to measure spin precession, even for very high-mass and short signals with two to three observable cycles. We do not find that the same morphological features consistently drive precession constraints: in some signals, precession inference hinges on the relationship between a loud merger and quiet pre-merger cycle, as was the case for GW190521, but this is not generically true. Our studies enable a morphological understanding of precession that can help bolster confidence in precession inference in the presence of signal or noise systematics.
Copyright and License
© 2025 American Physical Society.
Acknowledgement
We thank Harrison Siegel, Rhiannon Udall, Eliot Finch, and Will Farr for helpful discussions about ringdown analyses and parameter estimation, as well as Barry McKernan and K. E. Saavik Ford for insights into the expected astrophysical BBH inclination angle distribution. S. J. M. and K. C. were supported by NSF Grants PHY-2308770 and PHY-2409001. The Flatiron Institute is a division of the Simons Foundation. V. V. acknowledges support from NSF Grant No. PHY-2309301 and UMass Dartmouth’s Marine and Undersea Technology (MUST) Research Program funded by the Office of Naval Research (ONR) under Grant No. N00014-23-1-2141. S. H. was supported by the National Science Foundation Graduate Research Fellowship under Grant DGE-1745301. This material is based upon work supported by NSF’s LIGO Laboratory, which is a major facility fully funded by the National Science Foundation. The authors are thankful for LIGO Laboratory computing resources, funded by the National Science Foundation Grants PHY-0757058 and PHY-0823459, as well as the Hawk computing cluster provided by Cardiff University and supported by STFC Grants No. ST/I006285/1 and ST/V005618/1. This research has made use of data or software obtained from the Gravitational Wave Open Science Center [89,95,153], a service of LIGO Scientific Collaboration, Virgo Collaboration, and KAGRA. This material is based upon work supported by NSF’s LIGO Laboratory, which is a major facility fully funded by the National Science Foundation, as well as the Science and Technology Facilities Council (STFC) of the United Kingdom, the Max-Planck Society (MPS), and the State of Niedersachsen/Germany for support of the construction of Advanced LIGO and construction and operation of the GEO600 detector. Additional support for Advanced LIGO was provided by the Australian Research Council. Virgo is funded, through the European Gravitational Observatory (EGO), by the French Centre National de Recherche Scientifique (CNRS), the Italian Istituto Nazionale di Fisica Nucleare (INFN), and the Dutch Nikhef, with contributions by institutions from Belgium, Germany, Greece, Hungary, Ireland, Japan, Monaco, Poland, Portugal, and Spain. K. A. G. R. A. is supported by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan Society for the Promotion of Science (JSPS) in Japan, the National Research Foundation (NRF) and Ministry of Science and ICT (MSIT) in Korea, and Academia Sinica (AS) and the National Science and Technology Council (NSTC) in Taiwan.
Data Availability
Data necessary to reproduce figures and animations are available on Zenodo at Ref. [166]. The data release includes posteriors for 𝑀, 𝑞, 𝜒eff, and 𝜒p for each analysis. Additional data are available upon request.
Files
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Additional details
Related works
- Is new version of
- Discussion Paper: arXiv:2505.14573 (arXiv)
- Dataset: 10.5281/zenodo.15474960 (DOI)
Funding
- National Science Foundation
- PHY-2308770
- National Science Foundation
- PHY-2409001
- Simons Foundation
- National Science Foundation
- PHY-2309301
- Office of Naval Research
- N00014-23-1-2141
- National Science Foundation
- DGE-1745301
- National Science Foundation
- PHY-0757058
- National Science Foundation
- PHY-0823459
- Science and Technology Facilities Council
- ST/I006285/1
- Science and Technology Facilities Council
- ST/V005618/1
- Australian Research Council
- European Gravitational Observatory
- Centre National de la Recherche Scientifique
- Istituto Nazionale di Fisica Nucleare
- Ministry of Education, Culture, Sports, Science and Technology
- Japan Society for the Promotion of Science
- National Research Foundation of Korea
- Ministry of Science and ICT
- Academia Sinica
- National Science and Technology Council
Dates
- Accepted
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2025-10-17
Caltech Custom Metadata
- Caltech groups
- Astronomy Department , LIGO , TAPIR , Walter Burke Institute for Theoretical Physics , Division of Physics, Mathematics and Astronomy (PMA) , Physics Department
- Publication Status
- Published