---
OA_place: repository
OA_type: green
_id: '21126'
abstract:
- lang: eng
  text: Subparsec supermassive black hole (SMBH) binaries are expected to be common
    in active galactic nuclei as a result of the hierarchical buildup of galaxies
    via mergers. While direct evidence for these compact binaries is lacking, a few
    hundred candidates have been identified, most based on the apparent periodicities
    of their optical light curves. Since these signatures can be mimicked by active
    galactic nuclei red noise, additional evidence is needed to confirm their binary
    nature. Recurring self-lensing flares, occurring whenever the two BHs are aligned
    with the line of sight within their Einstein radii, have been suggested as additional
    binary signatures. Furthermore, in many cases, lensing flares are also predicted
    to contain a “dip,” whenever the lensed SMBH’s shadow is comparable in angular
    size to the binary’s Einstein radius. This feature would unambiguously confirm
    binaries and additionally identify SMBH shadows that are spatially unresolvable
    by high-resolution Very Long Baseline Interferometry (VLBI). Here we estimate
    the number of quasars for which these dips may be detectable by Legacy Survey
    of Space and Time (LSST) by extrapolating the quasar luminosity function to faint
    magnitudes and assuming that SMBH binaries are randomly oriented and have mass
    ratios following those in the Illustris simulations. Under plausible assumptions
    about quasar lifetimes, binary fractions, and Eddington ratios, we expect tens
    of thousands of detectable flares, of which several dozen contain measurable dips.
article_number: '063011'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Kevin
  full_name: Park, Kevin
  last_name: Park
- first_name: Chengcheng
  full_name: Xin, Chengcheng
  last_name: Xin
- first_name: Jordy
  full_name: Davelaar, Jordy
  last_name: Davelaar
- first_name: Zoltán
  full_name: Haiman, Zoltán
  id: 7c006e8c-cc0d-11ee-8322-cb904ef76f36
  last_name: Haiman
  orcid: 0000-0003-3633-5403
citation:
  ama: Park K, Xin C, Davelaar J, Haiman Z. Self-lensing flares from black hole binaries.
    IV. The number of detectable shadows. <i>Physical Review D</i>. 2025;111(6). doi:<a
    href="https://doi.org/10.1103/physrevd.111.063011">10.1103/physrevd.111.063011</a>
  apa: Park, K., Xin, C., Davelaar, J., &#38; Haiman, Z. (2025). Self-lensing flares
    from black hole binaries. IV. The number of detectable shadows. <i>Physical Review
    D</i>. American Physical Society. <a href="https://doi.org/10.1103/physrevd.111.063011">https://doi.org/10.1103/physrevd.111.063011</a>
  chicago: Park, Kevin, Chengcheng Xin, Jordy Davelaar, and Zoltán Haiman. “Self-Lensing
    Flares from Black Hole Binaries. IV. The Number of Detectable Shadows.” <i>Physical
    Review D</i>. American Physical Society, 2025. <a href="https://doi.org/10.1103/physrevd.111.063011">https://doi.org/10.1103/physrevd.111.063011</a>.
  ieee: K. Park, C. Xin, J. Davelaar, and Z. Haiman, “Self-lensing flares from black
    hole binaries. IV. The number of detectable shadows,” <i>Physical Review D</i>,
    vol. 111, no. 6. American Physical Society, 2025.
  ista: Park K, Xin C, Davelaar J, Haiman Z. 2025. Self-lensing flares from black
    hole binaries. IV. The number of detectable shadows. Physical Review D. 111(6),
    063011.
  mla: Park, Kevin, et al. “Self-Lensing Flares from Black Hole Binaries. IV. The
    Number of Detectable Shadows.” <i>Physical Review D</i>, vol. 111, no. 6, 063011,
    American Physical Society, 2025, doi:<a href="https://doi.org/10.1103/physrevd.111.063011">10.1103/physrevd.111.063011</a>.
  short: K. Park, C. Xin, J. Davelaar, Z. Haiman, Physical Review D 111 (2025).
date_created: 2026-01-31T09:29:42Z
date_published: 2025-03-04T00:00:00Z
date_updated: 2026-02-10T08:14:10Z
day: '04'
doi: 10.1103/physrevd.111.063011
extern: '1'
external_id:
  arxiv:
  - '2409.04583'
fulldoi: https://doi.org/10.1103/physrevd.111.063011
intvolume: '       111'
issue: '6'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://doi.org/10.48550/arXiv.2409.04583
month: '03'
oa: 1
oa_version: Preprint
publication: Physical Review D
publication_identifier:
  eissn:
  - 2470-0029
  issn:
  - 2470-0010
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
status: public
title: Self-lensing flares from black hole binaries. IV. The number of detectable
  shadows
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 111
year: '2025'
...