---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
PlanS_conform: '1'
_id: '22616'
abstract:
- lang: eng
  text: Accretion disks in active galactic nuclei (AGN) are promising sites for mergers
    of stellar-mass black holes (BHs) detectable via gravitational waves (GWs). These
    environments facilitate both in situ formation and dynamical capture of compact
    objects and their subsequent mergers. The uncertain origin of GW events detected
    by LIGO, Virgo, and KAGRA motivates searching for accompanying electromagnetic
    (EM) signatures. Here, we investigate postmerger EM flares associated with jets
    launched from merger remnants, as well as from the shocked ambient gas as the
    jet breaks out of the disk. We find that jet breakout produces luminous gamma-ray
    emission, detectable with MeV-band telescopes. Cooling emission from a shocked
    circum-BH minidisk, winds, and background AGN disk peaks in the UV and optical,
    with durations ranging from about an hour to a month, and can be identified through
    year-long monitoring of ∼103 AGNs with luminosities ranging from ∼1044 to ∼1045
    erg s−1. With a single set of parameters, this postmerger jet model produces gamma-ray,
    hard X-ray, and optical flares similar to those claimed to be associated with
    GW events. Furthermore, by incorporating a transition from a high- to low-angular-momentum
    accretion state after the merger, the model avoids excessive BH growth, alleviating
    tensions with hyper-Eddington accretion scenarios.
acknowledgement: We thank Wen-Biao Han for fruitful discussions on possible scenarios.
  H.T. is supported by The National Key R&D Program of China (grant No. 2024YFC2207700).
  S.S.K. was supported by Japan Society for the Promotion of Science (JSPS) KAKENHI
  grant numbers 22K14028, 21H04487, and 23H04899 and the Tohoku Initiative for Fostering
  Global Researchers for Interdisciplinary Sciences (TI-FRIS) of MEXT’s Strategic
  Professional Development Program for Young Researchers. Z.H. was supported by NASA
  grant 80NSSC22K0822 and NSF grant AST-2006176.
article_number: '121'
article_processing_charge: Yes
article_type: original
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: Shigeo S.
  full_name: Kimura, Shigeo S.
  last_name: Kimura
- first_name: Hassen M.
  full_name: Yesuf, Hassen M.
  last_name: Yesuf
- first_name: Hengxiao
  full_name: Guo, Hengxiao
  last_name: Guo
citation:
  ama: 'Tagawa H, Haiman Z, Kimura SS, Yesuf HM, Guo H. Electromagnetic flares from
    compact-object mergers in active galactic nucleus disks: Signatures and predictions.
    <i>The Astrophysical Journal</i>. 2026;1006(2). doi:<a href="https://doi.org/10.3847/1538-4357/ae7d29">10.3847/1538-4357/ae7d29</a>'
  apa: 'Tagawa, H., Haiman, Z., Kimura, S. S., Yesuf, H. M., &#38; Guo, H. (2026).
    Electromagnetic flares from compact-object mergers in active galactic nucleus
    disks: Signatures and predictions. <i>The Astrophysical Journal</i>. IOP Publishing.
    <a href="https://doi.org/10.3847/1538-4357/ae7d29">https://doi.org/10.3847/1538-4357/ae7d29</a>'
  chicago: 'Tagawa, Hiromichi, Zoltán Haiman, Shigeo S. Kimura, Hassen M. Yesuf, and
    Hengxiao Guo. “Electromagnetic Flares from Compact-Object Mergers in Active Galactic
    Nucleus Disks: Signatures and Predictions.” <i>The Astrophysical Journal</i>.
    IOP Publishing, 2026. <a href="https://doi.org/10.3847/1538-4357/ae7d29">https://doi.org/10.3847/1538-4357/ae7d29</a>.'
  ieee: 'H. Tagawa, Z. Haiman, S. S. Kimura, H. M. Yesuf, and H. Guo, “Electromagnetic
    flares from compact-object mergers in active galactic nucleus disks: Signatures
    and predictions,” <i>The Astrophysical Journal</i>, vol. 1006, no. 2. IOP Publishing,
    2026.'
  ista: 'Tagawa H, Haiman Z, Kimura SS, Yesuf HM, Guo H. 2026. Electromagnetic flares
    from compact-object mergers in active galactic nucleus disks: Signatures and predictions.
    The Astrophysical Journal. 1006(2), 121.'
  mla: 'Tagawa, Hiromichi, et al. “Electromagnetic Flares from Compact-Object Mergers
    in Active Galactic Nucleus Disks: Signatures and Predictions.” <i>The Astrophysical
    Journal</i>, vol. 1006, no. 2, 121, IOP Publishing, 2026, doi:<a href="https://doi.org/10.3847/1538-4357/ae7d29">10.3847/1538-4357/ae7d29</a>.'
  short: H. Tagawa, Z. Haiman, S.S. Kimura, H.M. Yesuf, H. Guo, The Astrophysical
    Journal 1006 (2026).
das_tickbox: '0'
date_created: 2026-08-02T22:01:52Z
date_published: 2026-08-01T00:00:00Z
date_updated: 2026-08-03T08:00:54Z
day: '01'
ddc:
- '520'
department:
- _id: ZoHa
doi: 10.3847/1538-4357/ae7d29
file:
- access_level: open_access
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  date_created: 2026-08-03T07:58:25Z
  date_updated: 2026-08-03T07:58:25Z
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file_date_updated: 2026-08-03T07:58:25Z
fulldoi: https://doi.org/10.3847/1538-4357/ae7d29
has_accepted_license: '1'
intvolume: '      1006'
issue: '2'
language:
- iso: eng
month: '08'
oa: 1
oa_version: Published Version
publication: The Astrophysical Journal
publication_identifier:
  eissn:
  - 1538-4357
  issn:
  - 0004-637X
publication_status: published
publisher: IOP Publishing
quality_controlled: '1'
researchdata_availability: no
scopus_import: '1'
status: public
supplementarymaterial: yes
title: 'Electromagnetic flares from compact-object mergers in active galactic nucleus
  disks: Signatures and predictions'
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: 1006
year: '2026'
...