Journal article
Black hole binaries in AGN accretion discs – II. Gas effects on black hole satellite scatterings
- Abstract:
- The black hole (BH) binaries in active galactic nuclei (AGN) are expected to form mainly through scattering encounters in the ambient gaseous medium. Recent simulations, including our own, have confirmed this formation pathway is highly efficient. We perform 3D smoothed particle hydrodynamics (SPH) simulations of BH scattering encounters in AGN discs. Using a range of impact parameters, we probe the necessary conditions for binary capture and how different orbital trajectories affect the dissipative effects from the gas. We identify a single range of impact parameters, typically of width ∼0.86−1.59 binary Hill radii depending on AGN disc density, that reliably leads to binary formation. The periapsis of the first encounter is the primary variable that determines the outcome of the initial scattering. We find an associated power law between the energy dissipated and the periapsis depth to be ΔE ∝ r−b with b = 0.42 ± 0.16, where deeper encounters dissipate more energy. Excluding accretion physics does not significantly alter these results. We identify the region of parameter space in initial energy versus impact parameter where a scattering leads to binary formation. Based on our findings, we provide a ready-to-use analytic criterion that utilizes these two pre-encounter parameters to determine the outcome of an encounter, with a reliability rate of >90 per cent. As the criterion is based directly on our simulations, it provides a reliable and highly physically motivated criterion for predicting binary scattering outcomes which can be used in population studies of BH binaries and mergers around AGN.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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(Preview, Version of record, pdf, 4.6MB, Terms of use)
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- Publisher copy:
- 10.1093/mnras/stad3641
Authors
+ Science and Technology Facilities Council
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- Funder identifier:
- https://ror.org/057g20z61
- Grant:
- ST/W000903/1
- ST/P002307/1
- ST/R002452/1
- ST/R00689X/1
- Publisher:
- Oxford University Press
- Journal:
- Monthly Notices of the Royal Astronomical Society More from this journal
- Volume:
- 527
- Issue:
- 4
- Pages:
- 10448-10468
- Publication date:
- 2023-12-01
- Acceptance date:
- 2023-11-12
- DOI:
- EISSN:
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1365-2966
- ISSN:
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0035-8711
- Language:
-
English
- Keywords:
- Pubs id:
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1611299
- Local pid:
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pubs:1611299
- Deposit date:
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2024-09-24
Terms of use
- Copyright holder:
- Rowan et al.
- Copyright date:
- 2023
- Rights statement:
- © 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
- Licence:
- CC Attribution (CC BY)
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