---
_id: '17688'
abstract:
- lang: eng
  text: Pulsar timing arrays (PTAs) are expected to detect gravitational waves (GWs)
    from individual low-redshift (z<1.5) compact supermassive (M>10^9 Msun) black
    hole (SMBH) binaries with orbital periods of approx. 0.1 - 10 yrs. Identifying
    the electromagnetic (EM) counterparts of these sources would provide confirmation
    of putative direct detections of GWs, present a rare opportunity to study the
    environments of compact SMBH binaries, and could enable the use of these sources
    as standard sirens for cosmology. Here we consider the feasibility of such an
    EM identification. We show that because the host galaxies of resolved PTA sources
    are expected to be exceptionally massive and rare, it should be possible to find
    unique hosts of resolved sources out to redshift z=0.2. At higher redshifts, the
    PTA error boxes are larger, and may contain as many as 100 massive-galaxy interlopers.
    The number of candidates, however, remains tractable for follow-up searches in
    upcoming wide-field EM surveys. We develop a toy model to characterize the dynamics
    and the thermal emission from a geometrically thin, gaseous disc accreting onto
    a PTA-source SMBH binary. Our model predicts that at optical and infrared frequencies,
    the source should appear similar to a typical luminous active galactic nucleus
    (AGN). However, owing to the evacuation of the accretion flow by the binary's
    tidal torques, the source might have an unusually low soft X-ray luminosity and
    weak UV and broad optical emission lines, as compared to an AGN powered by a single
    SMBH with the same total mass. For sources near z=1, the decrement in the rest-frame
    UV should be observable as an extremely red optical color. These properties would
    make the PTA sources stand out among optically luminous AGN, and could allow their
    unique identification.
alternative_title:
- Electromagnetic counterparts of PTA sources
article_processing_charge: No
article_type: original
author:
- first_name: Takamitsu
  full_name: Tanaka, Takamitsu
  last_name: Tanaka
- first_name: Kristen
  full_name: Menou, Kristen
  last_name: Menou
- first_name: Zoltán
  full_name: Haiman, Zoltán
  id: 7c006e8c-cc0d-11ee-8322-cb904ef76f36
  last_name: Haiman
citation:
  ama: Tanaka T, Menou K, Haiman Z. Electromagnetic counterparts of supermassive black
    hole binaries resolved by pulsar timing arrays. <i>Monthly Notices of the Royal
    Astronomical Society</i>. 2012;420(1):705-719. doi:<a href="https://doi.org/10.1111/j.1365-2966.2011.20083.x">10.1111/j.1365-2966.2011.20083.x</a>
  apa: Tanaka, T., Menou, K., &#38; Haiman, Z. (2012). Electromagnetic counterparts
    of supermassive black hole binaries resolved by pulsar timing arrays. <i>Monthly
    Notices of the Royal Astronomical Society</i>. Oxford University Press. <a href="https://doi.org/10.1111/j.1365-2966.2011.20083.x">https://doi.org/10.1111/j.1365-2966.2011.20083.x</a>
  chicago: Tanaka, Takamitsu, Kristen Menou, and Zoltán Haiman. “Electromagnetic Counterparts
    of Supermassive Black Hole Binaries Resolved by Pulsar Timing Arrays.” <i>Monthly
    Notices of the Royal Astronomical Society</i>. Oxford University Press, 2012.
    <a href="https://doi.org/10.1111/j.1365-2966.2011.20083.x">https://doi.org/10.1111/j.1365-2966.2011.20083.x</a>.
  ieee: T. Tanaka, K. Menou, and Z. Haiman, “Electromagnetic counterparts of supermassive
    black hole binaries resolved by pulsar timing arrays,” <i>Monthly Notices of the
    Royal Astronomical Society</i>, vol. 420, no. 1. Oxford University Press, pp.
    705–719, 2012.
  ista: Tanaka T, Menou K, Haiman Z. 2012. Electromagnetic counterparts of supermassive
    black hole binaries resolved by pulsar timing arrays. Monthly Notices of the Royal
    Astronomical Society. 420(1), 705–719.
  mla: Tanaka, Takamitsu, et al. “Electromagnetic Counterparts of Supermassive Black
    Hole Binaries Resolved by Pulsar Timing Arrays.” <i>Monthly Notices of the Royal
    Astronomical Society</i>, vol. 420, no. 1, Oxford University Press, 2012, pp.
    705–19, doi:<a href="https://doi.org/10.1111/j.1365-2966.2011.20083.x">10.1111/j.1365-2966.2011.20083.x</a>.
  short: T. Tanaka, K. Menou, Z. Haiman, Monthly Notices of the Royal Astronomical
    Society 420 (2012) 705–719.
date_created: 2024-09-06T08:23:06Z
date_published: 2012-01-23T00:00:00Z
date_updated: 2024-09-25T09:49:01Z
day: '23'
doi: 10.1111/j.1365-2966.2011.20083.x
extern: '1'
intvolume: '       420'
issue: '1'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://doi.org/10.1111/j.1365-2966.2011.20083.x
month: '01'
oa: 1
oa_version: Published Version
page: 705-719
publication: Monthly Notices of the Royal Astronomical Society
publication_identifier:
  issn:
  - 0035-8711
publication_status: published
publisher: Oxford University Press
quality_controlled: '1'
scopus_import: '1'
status: public
title: Electromagnetic counterparts of supermassive black hole binaries resolved by
  pulsar timing arrays
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 420
year: '2012'
...