---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
PlanS_conform: '1'
_id: '22713'
abstract:
- lang: eng
  text: Ground-based gravitational-wave (GW) observatories have detected approximately
    200 binary black hole (BH) mergers. The astrophysical origin of these events is
    debated, with evidence suggesting that at least a subset originated from dynamic
    environments characterized by frequent close encounters. Accretion disks in active
    galactic nuclei (AGNs) are of particular interest, as certain observed features
    could be more readily produced within such environments. In this paper, we investigate
    the expected properties of mergers in these environments, and their dependence
    on various parameters, using 1D N-body simulations combined with a comprehensive
    semianalytical model. In our fiducial model, the distributions of masses (m1 and
    m2) and mass ratios (q ≡ m2/m1 ≤ 1) are similar to those observed. However, they
    depend strongly on the lifetime and density of the AGN disk and on the number
    and accretion efficiency of BHs, with higher masses predicted as these quantities
    increase. The most massive mergers, such as GW231123, can be produced either by
    efficient gas accretion or by hierarchical mergers among ≥3 generations of BHs.
    The observed negative correlation between q and the average effective spin (χeff),
    along with the positive correlation between χeff and the chirp mass (Mchirp),
    can be explained by a combination of efficient gas accretion, which promotes spin
    alignment, and hierarchical mergers, which produce high-∣χeff∣ and low-q binaries.
    Hierarchical mergers can also explain the negative correlation between q and the
    dispersion of χeff, as well as the positive correlation between ∣χeff∣and Mchirp.
    We present a comprehensive study on how the expected distribution of each of these
    quantities depends on model parameters and assumptions, which will aid the interpretation
    of observed GW population properties.
acknowledgement: H.T. is supported by the National Science and Technology Major Project
  of China (No. 2024ZD1100601) and the National Key R&D Program of China (grant No.2024YFC2207700).
  Z.H. was supported by NASA grants 80NSSC22K0822 and 80NSSC24K0440. B.K. is supported
  by the Science and Technology Facilities Council grant No. ST/W000903/1. Simulations
  were carried out on Cray XD2000 at the Center for Computational Astrophysics, National
  Astronomical Observatory of Japan.
article_number: '67'
article_processing_charge: Yes
article_type: original
arxiv: 1
author:
- first_name: Hiromichi
  full_name: Tagawa, Hiromichi
  last_name: Tagawa
- first_name: Zoltán
  full_name: Haiman, Zoltán
  id: 7c006e8c-cc0d-11ee-8322-cb904ef76f36
  last_name: Haiman
  orcid: 0000-0003-3633-5403
- first_name: Bence
  full_name: Kocsis, Bence
  last_name: Kocsis
citation:
  ama: Tagawa H, Haiman Z, Kocsis B. Properties of black hole mergers in disks of
    active galactic nuclei. <i>The Astrophysical Journal</i>. 2026;1007(1). doi:<a
    href="https://doi.org/10.3847/1538-4357/ae8760">10.3847/1538-4357/ae8760</a>
  apa: Tagawa, H., Haiman, Z., &#38; Kocsis, B. (2026). Properties of black hole mergers
    in disks of active galactic nuclei. <i>The Astrophysical Journal</i>. IOP Publishing.
    <a href="https://doi.org/10.3847/1538-4357/ae8760">https://doi.org/10.3847/1538-4357/ae8760</a>
  chicago: Tagawa, Hiromichi, Zoltán Haiman, and Bence Kocsis. “Properties of Black
    Hole Mergers in Disks of Active Galactic Nuclei.” <i>The Astrophysical Journal</i>.
    IOP Publishing, 2026. <a href="https://doi.org/10.3847/1538-4357/ae8760">https://doi.org/10.3847/1538-4357/ae8760</a>.
  ieee: H. Tagawa, Z. Haiman, and B. Kocsis, “Properties of black hole mergers in
    disks of active galactic nuclei,” <i>The Astrophysical Journal</i>, vol. 1007,
    no. 1. IOP Publishing, 2026.
  ista: Tagawa H, Haiman Z, Kocsis B. 2026. Properties of black hole mergers in disks
    of active galactic nuclei. The Astrophysical Journal. 1007(1), 67.
  mla: Tagawa, Hiromichi, et al. “Properties of Black Hole Mergers in Disks of Active
    Galactic Nuclei.” <i>The Astrophysical Journal</i>, vol. 1007, no. 1, 67, IOP
    Publishing, 2026, doi:<a href="https://doi.org/10.3847/1538-4357/ae8760">10.3847/1538-4357/ae8760</a>.
  short: H. Tagawa, Z. Haiman, B. Kocsis, The Astrophysical Journal 1007 (2026).
das_tickbox: '0'
date_created: 2026-08-16T22:01:43Z
date_published: 2026-08-10T00:00:00Z
date_updated: 2026-08-18T09:05:25Z
day: '10'
ddc:
- '520'
department:
- _id: ZoHa
doi: 10.3847/1538-4357/ae8760
external_id:
  arxiv:
  - '2604.25994'
file:
- access_level: open_access
  checksum: 1531fd5997b054d26e99d44ccc7f8ff5
  content_type: application/pdf
  creator: dernst
  date_created: 2026-08-18T09:01:50Z
  date_updated: 2026-08-18T09:01:50Z
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  file_size: 2246236
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file_date_updated: 2026-08-18T09:01:50Z
has_accepted_license: '1'
intvolume: '      1007'
issue: '1'
language:
- iso: eng
month: '08'
oa: 1
oa_version: Published Version
publication: The Astrophysical Journal
publication_identifier:
  eissn:
  - 1538-4357
  issn:
  - 000-4637X
publication_status: published
publisher: IOP Publishing
quality_controlled: '1'
researchdata_availability: no
scopus_import: '1'
status: public
supplementarymaterial: no
title: Properties of black hole mergers in disks of active galactic nuclei
tmp:
  image: /images/cc_by.png
  legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 1007
year: '2026'
...