The Astrophysical Journal (Jan 2023)

Observational Evidence of a Centi-parsec Supermassive Black Hole Binary Existing in the Nearby Galaxy M81

  • Wu Jiang,
  • Zhiqiang Shen,
  • Ivan Martí-Vidal,
  • Zhen Yan,
  • Lei Huang,
  • Roman Gold,
  • Ya-Ping Li,
  • Fuguo Xie,
  • Noriyuki Kawaguchi

DOI
https://doi.org/10.3847/1538-4357/ad063d
Journal volume & issue
Vol. 959, no. 1
p. 11

Abstract

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Studying a centi-parsec supermassive black hole binary (SMBHB) would allow us to explore a new parameter space in active galactic nuclei, and these objects are also potential sources of gravitational waves. We report evidence that an SMBHB with an orbital period of ∼30 yr may be resident in the nearby galactic nucleus M81. This orbital period and the known mass of M81 imply an orbital separation of ∼0.02 pc. The jet emanating from the primary black hole showed a short period of jet wobbling at ∼16.7 yr, superposing a long-term precession at a timescale of several hundred years. Periodic radio and X-ray outbursts were also found two times per orbital period, which could be explained by a double-peaked mass accretion rate variation per binary orbit. If confirmed, M81 would be one of the closest SMBHB candidates, providing a rare opportunity to study the final parsec problem .

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