Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

A candidate sub-parsec supermassive binary black hole system


The role of mergers in producing galaxies, together with the finding that most large galaxies harbour black holes in their nuclei1, implies that binary supermassive black hole systems should be common. Here we report that the quasar SDSS J153636.22+044127.0 is a plausible example of such a system. This quasar shows two broad-line emission systems, separated in velocity by 3,500 km s-1. A third system of unresolved absorption lines has an intermediate velocity. These characteristics are unique among known quasars. We interpret this object as a binary system of two black holes, having masses of 107.3 and 108.9 solar masses separated by 0.1 parsec with an orbital period of 100 years.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: The observed spectrum from the SDSS archive of the quasar SDSS J1536+0441.
Figure 2: Cross-correlation between the 4,200–4,450 Å region of the spectrum of J1536+0441 and the corresponding region of a composite quasar spectrum12.

Similar content being viewed by others


  1. Magorrian, J. et al. The demography of massive dark objects in galaxy centers. Astron. J. 115, 2285–2305 (1998)

    Article  ADS  Google Scholar 

  2. Komossa, S., Zhou, H. & Lu, H. A recoiling supermassive black hole in the quasar SDSS J092712.65+294344.0? Astrophys. J. 678, L81–L84 (2008)

    Article  ADS  CAS  Google Scholar 

  3. Bogdanovic, T., Eracleous, M. & Sigurdsson, S. SDSS J092712.65+294344.0: Recoiling black hole or a sub-parsec binary candidate? Preprint at 〈〉 (2008)

  4. Dotti, M. et al. SDSSJ092712.65+294344.0: A candidate massive black hole binary. Preprint at 〈〉 (2008)

  5. Heckman, T. M., Krolik, J. H., Moran, S., Schnittman, J. & Gezari, S. SDSSJ092712.65+294344.0: NGC 1275 at z = 0.7? Preprint at 〈〉 (2008)

  6. Shields, G. A., Bonning, E. W. & Salviander, S. Comment on the black hole recoil candidate quasar SDSS J092712.65+294344.0. Preprint at 〈〉 (2008)

  7. Schneider, D. P. et al. The Sloan Digital Sky Survey quasar catalog. IV. Fifth data release. Astron. J. 134, 102–117 (2007)

    Article  ADS  Google Scholar 

  8. Appenzeller, I. & Wagner, S. J. Forbidden high-ionization lines in QSO spectra. Astron. Astrophys. 250, 57–61 (1991)

    ADS  CAS  Google Scholar 

  9. Moore, D. & Cohen, R. D. Narrow-line region kinematics in Seyfert nuclei. Astrophys. J. 433, 602–624 (1994)

    Article  ADS  CAS  Google Scholar 

  10. Boroson, T. A. & Meyers, K. A. The optical properties of IR-selected and Mg II broad absorption line quasars. Astrophys. J. 397, 442–451 (1992)

    Article  ADS  CAS  Google Scholar 

  11. Vanden Berk, D. E. et al. Composite quasar spectra from the Sloan Digital Sky Survey. Astron. J. 122, 549–565 (2001)

    Article  ADS  Google Scholar 

  12. Hu, C. et al. A systematic analysis of Fe II emission in quasars: Evidence for inflow to the central black hole. Astrophys. J. 687, 78–96 (2008)

    Article  ADS  CAS  Google Scholar 

  13. Denney, K. D., Peterson, B. M., Dietrich, M., Vestergaard, M. & Bentz, M. C. Systematic uncertainties in black hole masses determined from single epoch spectra. Preprint at 〈〉 (2008)

  14. Sillanpää, A., Haarala, S., Valtonen, M. J., Sundelius, B. & Byrd, G. G. OJ 287: Binary pair of supermassive black holes. Astrophys. J. 325, 628–634 (1988)

    Article  ADS  Google Scholar 

  15. Valtonen, M. J. et al. A massive binary black-hole system in OJ 287 and a test of general relativity. Nature 452, 851–853 (2008)

    Article  ADS  CAS  Google Scholar 

  16. Peters, P. C. Gravitational radiation and the motion of two point masses. Phys. Rev. 136, 1224–1232 (1964)

    Article  ADS  Google Scholar 

  17. Milosavljevic, M. & Merritt, D. Long term evolution of massive black hole binaries. Astrophys. J. 596, 860–878 (2003)

    Article  ADS  Google Scholar 

  18. Gould, A. & Rix, H. Binary black hole mergers from planet-like migrations. Astrophys. J. 532, L29–L32 (2000)

    Article  ADS  CAS  Google Scholar 

  19. Cuadra, J., Armitage, P. J., Alexander, R. D. & Begelman, M. C. Massive black hole binary mergers within sub-pc scale gas disks. Mon. Not. R. Astron. Soc. (in the press)

  20. Richards, G. T. et al. The Sloan Digital Sky Survey quasar survey: Quasar luminosity function from Data Release 3. Astron. J. 131, 2766–2787 (2006)

    Article  ADS  CAS  Google Scholar 

  21. Conselice, C. J., Gallagher, J. S. & Wyse, R. F. G. On the nature of the NGC 1275 system. Astron. J. 122, 2281–2300 (2001)

    Article  ADS  CAS  Google Scholar 

Download references


NOAO is operated by the Association of Universities for Research in Astronomy (AURA), Inc. under cooperative agreement with the National Science Foundation (NSF). This paper has used data from the SDSS archive, the 2MASS archive, the ROSAT archive at the High Energy Astrophysics Science Archive Research Center (HEASARC), provided by NASA's Goddard Space Flight Center, the FIRST survey, and the NVSS. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the NSF, the US Department of Energy, the National Aeronautics and Space Administration (NASA), the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS website is at The 2MASS is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by NASA and the NSF.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Todd A. Boroson.

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Cite this article

Boroson, T., Lauer, T. A candidate sub-parsec supermassive binary black hole system. Nature 458, 53–55 (2009).

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing