---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
PlanS_conform: '1'
_id: '21844'
abstract:
- lang: eng
  text: Little red dots (LRDs) are a newly identified class of broad-line active galactic
    nuclei (AGNs) with a distinctive V-shaped spectrum characterized by red optical
    and blue UV continuum emission. Their high abundance at redshifts of z ∼ 6–8 and
    decline at lower redshifts suggest a transient origin. We propose that the spectral
    shape of LRDs originates from compact binary black hole systems, in which each
    black hole is surrounded by a mini-disk and embedded within a larger circumbinary
    disk. With a binary separation of ≲103 Schwarzschild radii, the Wien tail of a
    T ≃ 5000 K blackbody spectrum at the inner edge of the circumbinary disk produces
    the red optical emission, while the mini-disks power the UV continuum. Binary
    torques carve out a gap between the circumbinary disk and the mini-disks, setting
    the turnover wavelength of the V-shaped spectrum around the Balmer limit. This
    scenario naturally reproduces LRD spectra requiring only modest dust attenuation
    (AV ≲ 1 mag), resolving overestimated luminosities for LRDs in previous studies
    and alleviating a tension with the so-called Sołtan argument. This model predicts
    distinct spectral evolution as the binary orbit decays through binary disk interactions
    and gravitational-wave (GW) emission, linking early-stage “proto-LRD” binaries
    to the broader AGN population and late-stage “LRD descendants” to coalescing binaries
    detectable in GW experiments.
acknowledgement: We greatly thank Kenta Hotokezaka and Hanpu Liu for constructive
  discussions. K.I., J.S., X.C., and L.C.H. acknowledge support from National Natural
  Science Foundation of China (grant Nos. 12573015, 1251101148, 12233001, and 12473037),
  the Beijing Natural Science Foundation (grant No. IS25003), and the China Manned
  Space Program (grant No. CMS-CSST-2025-A09). J.S. is also supported by “The Fundamental
  Research Funds for the Central Universities, Peking University” (grant No. 7100604896).
  Z.H. acknowledges support by US NSF grant AST-2006176 and by NASA grant Nos. 80NSSC24K0440
  and 80NSSC22K0822.
article_number: '25'
article_processing_charge: Yes
article_type: original
arxiv: 1
author:
- first_name: Kohei
  full_name: Inayoshi, Kohei
  last_name: Inayoshi
- first_name: Jinyi
  full_name: Shangguan, Jinyi
  last_name: Shangguan
- first_name: Xian
  full_name: Chen, Xian
  last_name: Chen
- first_name: Luis C.
  full_name: Ho, Luis C.
  last_name: Ho
- first_name: Zoltán
  full_name: Haiman, Zoltán
  id: 7c006e8c-cc0d-11ee-8322-cb904ef76f36
  last_name: Haiman
  orcid: 0000-0003-3633-5403
citation:
  ama: Inayoshi K, Shangguan J, Chen X, Ho LC, Haiman Z. The emergence of Little Red
    Dots from binary massive black holes. <i>The Astrophysical Journal</i>. 2026;1002(1).
    doi:<a href="https://doi.org/10.3847/1538-4357/ae548d">10.3847/1538-4357/ae548d</a>
  apa: Inayoshi, K., Shangguan, J., Chen, X., Ho, L. C., &#38; Haiman, Z. (2026).
    The emergence of Little Red Dots from binary massive black holes. <i>The Astrophysical
    Journal</i>. IOP Publishing. <a href="https://doi.org/10.3847/1538-4357/ae548d">https://doi.org/10.3847/1538-4357/ae548d</a>
  chicago: Inayoshi, Kohei, Jinyi Shangguan, Xian Chen, Luis C. Ho, and Zoltán Haiman.
    “The Emergence of Little Red Dots from Binary Massive Black Holes.” <i>The Astrophysical
    Journal</i>. IOP Publishing, 2026. <a href="https://doi.org/10.3847/1538-4357/ae548d">https://doi.org/10.3847/1538-4357/ae548d</a>.
  ieee: K. Inayoshi, J. Shangguan, X. Chen, L. C. Ho, and Z. Haiman, “The emergence
    of Little Red Dots from binary massive black holes,” <i>The Astrophysical Journal</i>,
    vol. 1002, no. 1. IOP Publishing, 2026.
  ista: Inayoshi K, Shangguan J, Chen X, Ho LC, Haiman Z. 2026. The emergence of Little
    Red Dots from binary massive black holes. The Astrophysical Journal. 1002(1),
    25.
  mla: Inayoshi, Kohei, et al. “The Emergence of Little Red Dots from Binary Massive
    Black Holes.” <i>The Astrophysical Journal</i>, vol. 1002, no. 1, 25, IOP Publishing,
    2026, doi:<a href="https://doi.org/10.3847/1538-4357/ae548d">10.3847/1538-4357/ae548d</a>.
  short: K. Inayoshi, J. Shangguan, X. Chen, L.C. Ho, Z. Haiman, The Astrophysical
    Journal 1002 (2026).
date_created: 2026-05-10T22:02:14Z
date_published: 2026-05-01T00:00:00Z
date_updated: 2026-05-11T07:09:12Z
day: '01'
ddc:
- '520'
department:
- _id: ZoHa
doi: 10.3847/1538-4357/ae548d
external_id:
  arxiv:
  - '2505.05322'
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has_accepted_license: '1'
intvolume: '      1002'
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language:
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month: '05'
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'
scopus_import: '1'
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title: The emergence of Little Red Dots from binary massive black holes
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