---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
_id: '21712'
abstract:
- lang: eng
  text: Supermassive black hole binary (SMBHB) systems are expected to form as a consequence
    of galaxy mergers. At subparsec separations, SMBHBs can be identified as quasars
    with periodic variability, with previous periodicity searches uncovering significant
    candidates. However, these searches focused primarily on sinusoidal signals, while
    theoretical models and hydrodynamical simulations predict that binaries produce
    more complex non-sinusoidal pulse shapes. Here we examine the efficacy of the
    Lomb–Scargle periodogram (LSP; one of the most popular tools for periodicity searches
    in unevenly sampled lightcurves) to detect periodicities with a sawtooth shape
    mimicking results of hydrodynamical simulations. We simulate idealized well-sampled
    lightcurves, lightcurves that mimic the data in the Palomar Transient Factory
    (PTF) analyzed in M. Charisi et al. (2016), and lightcurves that resemble our
    expectations for single-band data in the upcoming Legacy Survey of Space and Time
    (LSST) of the Rubin Observatory. We approximate quasar variability with a damped
    random walk (DRW) model, inject sinusoidal and sawtooth pulse shapes, and assess
    their statistical significance. We find that in the presence of red noise, the
    LSP detects a relatively low fraction of the sinusoidal signals (∼45%, ∼24%, and
    ∼23%, in the PTF-like, idealized, and LSST-like lightcurves, respectively). The
    fraction is significantly reduced for sawtooth periodicity (with only ∼9% in PTF-like
    and ∼1% in idealized and LSST-like lightcurves). These low recovery rates imply
    that previous searches have missed the large majority of binaries. They also have
    significant implications for the detection of SMBHBs in upcoming LSST necessitating
    the development of advanced tools that go beyond the simple LSP.
acknowledgement: M.C. acknowledges support by the European Union (ERC; MMMonsters,
  101117624). This work was also supported in part by NASA grants 80NSSC24K0440 and
  80NSSC22K0822. This research used the resources of the Center for Institutional
  Research Computing at Washington State University.
article_number: '316'
article_processing_charge: Yes
article_type: original
author:
- first_name: Allison
  full_name: Lin, Allison
  last_name: Lin
- first_name: Maria
  full_name: Charisi, Maria
  last_name: Charisi
- first_name: Zoltán
  full_name: Haiman, Zoltán
  id: 7c006e8c-cc0d-11ee-8322-cb904ef76f36
  last_name: Haiman
  orcid: 0000-0003-3633-5403
citation:
  ama: Lin A, Charisi M, Haiman Z. Lomb-scargle periodogram struggles with non-sinusoidal
    supermassive Black Hole binary signatures in quasar lightcurves. <i>The Astrophysical
    Journal</i>. 2026;997(2). doi:<a href="https://doi.org/10.3847/1538-4357/ae29a7">10.3847/1538-4357/ae29a7</a>
  apa: Lin, A., Charisi, M., &#38; Haiman, Z. (2026). Lomb-scargle periodogram struggles
    with non-sinusoidal supermassive Black Hole binary signatures in quasar lightcurves.
    <i>The Astrophysical Journal</i>. IOP Publishing. <a href="https://doi.org/10.3847/1538-4357/ae29a7">https://doi.org/10.3847/1538-4357/ae29a7</a>
  chicago: Lin, Allison, Maria Charisi, and Zoltán Haiman. “Lomb-Scargle Periodogram
    Struggles with Non-Sinusoidal Supermassive Black Hole Binary Signatures in Quasar
    Lightcurves.” <i>The Astrophysical Journal</i>. IOP Publishing, 2026. <a href="https://doi.org/10.3847/1538-4357/ae29a7">https://doi.org/10.3847/1538-4357/ae29a7</a>.
  ieee: A. Lin, M. Charisi, and Z. Haiman, “Lomb-scargle periodogram struggles with
    non-sinusoidal supermassive Black Hole binary signatures in quasar lightcurves,”
    <i>The Astrophysical Journal</i>, vol. 997, no. 2. IOP Publishing, 2026.
  ista: Lin A, Charisi M, Haiman Z. 2026. Lomb-scargle periodogram struggles with
    non-sinusoidal supermassive Black Hole binary signatures in quasar lightcurves.
    The Astrophysical Journal. 997(2), 316.
  mla: Lin, Allison, et al. “Lomb-Scargle Periodogram Struggles with Non-Sinusoidal
    Supermassive Black Hole Binary Signatures in Quasar Lightcurves.” <i>The Astrophysical
    Journal</i>, vol. 997, no. 2, 316, IOP Publishing, 2026, doi:<a href="https://doi.org/10.3847/1538-4357/ae29a7">10.3847/1538-4357/ae29a7</a>.
  short: A. Lin, M. Charisi, Z. Haiman, The Astrophysical Journal 997 (2026).
date_created: 2026-04-12T22:01:49Z
date_published: 2026-02-01T00:00:00Z
date_updated: 2026-05-04T10:26:59Z
day: '01'
ddc:
- '520'
department:
- _id: ZoHa
doi: 10.3847/1538-4357/ae29a7
file:
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  date_created: 2026-05-04T10:24:49Z
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has_accepted_license: '1'
intvolume: '       997'
issue: '2'
language:
- iso: eng
month: '02'
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'
status: public
title: Lomb-scargle periodogram struggles with non-sinusoidal supermassive Black Hole
  binary signatures in quasar lightcurves
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: 997
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...