Gravitational-wave observations provide the unique opportunity of studying black hole formation channels and histories—but only if we can identify their origin. One such formation mechanism is the dynamical synthesis of black hole binaries in dense stellar systems. Given the expected isotropic distribution of component spins of binary black holes in gas-free dynamical environments, the presence of antialigned or in-plane spins with respect to the orbital angular momentum is considered a tell-tale sign of a merger's dynamical origin. Even in the scenario where birth spins of black holes are low, hierarchical mergers attain large component spins due to the orbital angular momentum of the prior merger. However, measuring such spin configurations is difficult. Here, we quantify the efficacy of the spin parameters encoding aligned-spin (χeff) and in-plane spin (χp) at classifying such hierarchical systems. Using Monte Carlo cluster simulations to generate a realistic distribution of hierarchical merger parameters from globular clusters, we can infer mergers' χeff and χp. The cluster populations are simulated using Advanced LIGO-Virgo sensitivity during the detector network's third observing period and projections for design sensitivity. Using a "likelihood-ratio"-based statistic, we find that ∼2% of the recovered population by the current gravitational-wave detector network has a statistically significant χp measurement, whereas no χeff measurement was capable of confidently determining a system to be antialigned with the orbital angular momentum at current detector sensitivities. These results indicate that measuring spin-precession through χp is a more detectable signature of hierarchical mergers and dynamical formation than antialigned spins.
Spin Doctors: How to Diagnose a Hierarchical Merger Origin
- Creators
- Payne, Ethan
- Kremer, Kyle
- Zevin, Michael
Abstract
Copyright and License
© 2024. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Acknowledgement
The authors thank Zoheyr Doctor, Christopher Berry, and Parthapratim Mahapatra for their insightful comments on the Letter. Support for K.K. was provided by NASA through the NASA Hubble Fellowship grant HST-HF2-51510 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. M.Z. gratefully acknowledges funding from the Brinson Foundation in support of astrophysics research at the Adler Planetarium.
The authors are grateful for computational resources provided by the LIGO Laboratory and supported by National Science Foundation Grants PHY-0757058 and PHY-0823459. This material is based upon work supported by NSF's LIGO Laboratory, which is a major facility fully funded by the National Science Foundation. LIGO was constructed by the California Institute of Technology and Massachusetts Institute of Technology with funding from the National Science Foundation and operates under cooperative agreement PHY-1764464. This paper carries LIGO Document Number LIGO-P2400050.
Software References
Bilby (Ashton et al. 2019; Romero-Shaw et al. 2020); dynesty (Speagle 2020); iPython (Pérez & Granger 2007); Matplotlib (Hunter 2007); NumPy (Harris et al. 2020); Pandas (Wes McKinney 2010); SciPy (Virtanen et al. 2020).
Files
Name | Size | Download all |
---|---|---|
md5:0e34c32f895dc6526554993d24b1a148
|
10.8 MB | Preview Download |
Additional details
- ISSN
- 2041-8213
- National Aeronautics and Space Administration
- NASA Hubble Fellowship HST-HF2-51510
- National Aeronautics and Space Administration
- NAS5-26555
- Brinson Foundation
- National Science Foundation
- PHY-0757058
- National Science Foundation
- PHY-0823459
- National Science Foundation
- PHY-1764464
- Caltech groups
- LIGO, TAPIR
- Other Numbering System Name
- LIGO Document
- Other Numbering System Identifier
- LIGO-P2400050