Journal article
Spin evolution of stellar-mass black hole binaries in active galactic nuclei
- Abstract:
- The astrophysical origin of gravitational-wave (GW) events is one of the most timely problems in the wake of the LIGO/Virgo discoveries. In active galactic nuclei (AGNs), binaries form and evolve efficiently by dynamical interactions and gaseous dissipation. Previous studies have suggested that binary black hole (BBH) mergers in AGN disks can contribute significantly to BBH mergers observed by GW interferometers. Here we examine the distribution of the effective spin parameter χ eff of this GW source population. We extend our semi-analytical model of binary formation and evolution in AGN disks by following the evolution of the binary orbital angular momenta and black hole (BH) spins. BH spins change due to gas accretion and BH mergers, while the binary orbital angular momenta evolve due to gas accretion and binary–single interactions. We find that the distribution of χ eff predicted by our AGN model is similar to the distribution observed during LIGO/Virgo O1 and O2. On the other hand, if radial migration of BHs is inefficient, χ eff is skewed toward higher values than the observed distribution, because of the paucity of scattering events that would randomize spin directions relative to the orbital plane. We suggest that high binary masses and the positive correlation between binary mass and the standard deviation of χ eff for chirp masses up to $\approx 20\,{M}_{\odot }$ can be possible signatures for mergers originating in AGN disks. Finally, hierarchical mergers in AGN disks naturally produce properties of the recent GW event GW190412, including a low mass ratio, a high primary BH spin, and a significant spin component in the orbital plane.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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(Preview, Version of record, 3.1MB, Terms of use)
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- Publisher copy:
- 10.3847/1538-4357/aba2cc
Authors
- Publisher:
- IOP Publishing
- Journal:
- Astrophysical Journal More from this journal
- Volume:
- 899
- Issue:
- 1
- Article number:
- 26
- Publication date:
- 2020-08-10
- Acceptance date:
- 2020-07-02
- DOI:
- EISSN:
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1538-4357
- ISSN:
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0004-637X
- Language:
-
English
- Keywords:
- Pubs id:
-
1128031
- Local pid:
-
pubs:1128031
- Deposit date:
-
2020-08-24
Terms of use
- Copyright holder:
- Tagawa et al.
- Copyright date:
- 2020
- Rights statement:
- ©2020. The Author(s). Published by the American Astronomical Society.
- Notes:
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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.
- Licence:
- CC Attribution (CC BY)
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