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.

Bright radio emission from an ultraluminous stellar-mass microquasar in M 31


A subset of ultraluminous X-ray sources (those with luminosities of less than 1040 erg s−1; ref. 1) are thought to be powered by the accretion of gas onto black holes with masses of 5–20, probably by means of an accretion disk2,3. The X-ray and radio emission are coupled in such Galactic sources; the radio emission originates in a relativistic jet thought to be launched from the innermost regions near the black hole4,5, with the most powerful emission occurring when the rate of infalling matter approaches a theoretical maximum (the Eddington limit). Only four such maximal sources are known in the Milky Way6, and the absorption of soft X-rays in the interstellar medium hinders the determination of the causal sequence of events that leads to the ejection of the jet. Here we report radio and X-ray observations of a bright new X-ray source in the nearby galaxy M 31, whose peak luminosity exceeded 1039 erg s−1. The radio luminosity is extremely high and shows variability on a timescale of tens of minutes, arguing that the source is highly compact and powered by accretion close to the Eddington limit onto a black hole of stellar mass. Continued radio and X-ray monitoring of such sources should reveal the causal relationship between the accretion flow and the powerful jet emission.

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

Access options

Rent or buy this article

Prices vary by article type



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

Figure 1: Evolution of the X-ray luminosity and spectrum over time.
Figure 2: Summary of the radio observations.


  1. Walton, D., Roberts, T., Mateos, S. & Heard, V. 2XMM ultraluminous X-ray source candidates in nearby galaxies. Mon. Not. R. Astron. Soc. 416, 1844–1861 (2011)

    Article  ADS  Google Scholar 

  2. Shakura, N. & Sunyaev, R. Black holes in binary systems. Observational appearance. Astron. Astrophys. 24, 337–355 (1973)

    ADS  Google Scholar 

  3. Middleton, M., Sutton, A., Roberts, T., Jackson, F. & Done, C. The missing link: a low-mass X-ray binary in M 31 seen as an ultraluminous X-ray source. Mon. Not. R. Astron. Soc. 420, 2969–2977 (2012)

    Article  ADS  Google Scholar 

  4. Mirabel, I. & Rodriguez, L. A superluminal source in the Galaxy. Nature 371, 46–48 (1994)

    Article  ADS  Google Scholar 

  5. Fender, R., Belloni, T. & Gallo, E. Towards a unified model for black hole X-ray binary jets. Mon. Not. R. Astron. Soc. 355, 1105–1118 (2004)

    Article  ADS  CAS  Google Scholar 

  6. Grimm, H., Gilfanov, M. & Sunyaev, R. The Milky Way in X-rays for an outside observer. Log(N)–log(S) and luminosity function of X-ray binaries from RXTE/ASM data. Astron. Astrophys. 391, 923–944 (2002)

    Article  ADS  Google Scholar 

  7. Henze, M. et al. XMMU J004243.6+412519—a new X-ray transient in M 31 seen with XMM-Newton. Astronomer’s Telegram ATel #3890, (2012)

  8. Monachesi, A. et al. The deepest Hubble Space Telescope color–magnitude diagram of M32. Evidence for intermediate-age populations. Astrophys. J. 727, 55 (2011)

    Article  ADS  Google Scholar 

  9. Remillard, R. & McClintock, J. X-ray properties of black-hole binaries. Annu. Rev. Astron. Astrophys. 44, 49–92 (2006)

    Article  ADS  Google Scholar 

  10. Dunn, R., Fender, R., Körding, E., Belloni, T. & Cabanac, C. A global spectral study of black hole X-ray binaries. Mon. Not. R. Astron. Soc. 403, 61–82 (2010)

    Article  ADS  CAS  Google Scholar 

  11. Feng, H. & Soria, R. Ultraluminous X-ray sources in the Chandra and XMM-Newton era. N. Astron. Rev. 55, 166–183 (2011)

    Article  ADS  Google Scholar 

  12. Kong, A., DiStefano, R., Garcia, M. & Greiner, J. Chandra studies of the X-ray point source luminosity functions of M 31. Astrophys. J. 585, 298–304 (2003)

    Article  ADS  Google Scholar 

  13. Ueda, Y., Yamaoka, K. & Remillard, R. GRS 1915+105 in ‘soft state’: nature of accretion disk wind and origin of X-ray emission. Astrophys. J. 695, 888–899 (2009)

    Article  ADS  CAS  Google Scholar 

  14. Abramowicz, M., Czerny, B., Lasota, J.-P. & Szuszkiewicz, E. Slim accretion disks. Astrophys. J. 332, 646–658 (1988)

    Article  ADS  Google Scholar 

  15. Middleton, M., Sutton, A. & Roberts, T. X-ray spectral evolution in the ultraluminous X-ray source M33 X-8. Mon. Not. R. Astron. Soc. 417, 464–471 (2011)

    Article  ADS  Google Scholar 

  16. King, A. Masses, beaming and Eddington ratios in ultraluminous X-ray sources. Mon. Not. R. Astron. Soc. 393, L41–L44 (2009)

    Article  ADS  Google Scholar 

  17. Feng, H. & Kaaret, P. Spectral states and evolution of ultraluminous X-ray sources. Astrophys. J. 696, 1712–1726 (2009)

    Article  ADS  CAS  Google Scholar 

  18. Cseh, D. et al. Black hole powered nebulae and a case study of the ultraluminous X-ray source IC 342 X-1. Astrophys. J. 749, 17 (2012)

    Article  ADS  Google Scholar 

  19. Merloni, A., Heinz, S. & di Matteo, T. A fundamental plane of black hole activity. Mon. Not. R. Astron. Soc. 345, 1057–1076 (2003)

    Article  ADS  Google Scholar 

  20. Plotkin, R., Markoff, S., Kelly, B., Körding, E. & Anderson, S. Using the fundamental plane of black hole activity to distinguish X-ray processes from weakly accreting black holes. Mon. Not. R. Astron. Soc. 419, 267–286 (2012)

    Article  ADS  Google Scholar 

  21. Gallo, E., Fender, R. & Pooley, G. A universal radio-X-ray correlation in low/hard state black hole binaries. Mon. Not. R. Astron. Soc. 344, 60–72 (2003)

    Article  ADS  Google Scholar 

  22. Kaiser, C., Sunyaev, R. & Spruit, H. Internal shock model for microquasars. Astron. Astrophys. 356, 975–988 (2000)

    ADS  Google Scholar 

  23. King, A. The brightest black holes. Mon. Not. R. Astron. Soc. 335, L13–L16 (2002)

    Article  ADS  Google Scholar 

  24. Fender, R. & Belloni, T. GRS 1915+105 and the disc–jet coupling in accreting black hole systems. Annu. Rev. Astron. Astrophys. 42, 317–364 (2004)

    Article  ADS  CAS  Google Scholar 

  25. Pooley, G. & Fender, R. The variable radio emission from GRS 1915+105. Mon. Not. R. Astron. Soc. 292, 925–933 (1997)

    Article  ADS  Google Scholar 

  26. Corbel, S. et al. A giant radio flare from Cygnus X-3 with associated γ-ray emission. Mon. Not. R. Astron. Soc. 421, 2947–2955 (2012)

    Article  ADS  Google Scholar 

  27. Orosz, J. A. et al. A black hole in the superluminal source SAX J1819.3−2525 (V4641 Sgr). Astrophys. J. 555, 489–503 (2001)

    Article  ADS  CAS  Google Scholar 

  28. Hjellming, R. M. et al. Light curves and radio structure of the 1999 September transient event in V4641 Sagittarii ( = XTE J1819–254 = SAX J1819.3–2525). Astrophys. J. 544, 977–992 (2000)

    Article  ADS  Google Scholar 

  29. Vilardell, F., Ribas, I. & Jordi, C. Eclipsing binaries suitable for distance determination in the Andromeda galaxy. Astron. Astrophys. 459, 321–331 (2006)

    Article  ADS  Google Scholar 

  30. Soria, R. et al. The birth of an ultraluminous X-ray source in M83. Astrophys. J. 750, 152 (2012)

    Article  ADS  Google Scholar 

Download references


We thank C. Trott and R. Soria for discussions, and C. Gough for making his code available. This work was supported by a Science and Technology Facilities Council (STFC) standard grant (M.J.M.), Netherlands Organization for Scientific Research Vidi Fellowship (S.M.), European Research Council partial funding (R.F.) and grant number BMWI/DLR, FKZ 50 OR 1010 (M. Henze). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We thank the staff of the Mullard Radio Astronomy Observatory for their assistance in the commissioning and operation of AMI, which is supported by Cambridge University and the STFC. This work is based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. This research has also made use of data obtained from NASA’s Swift and Chandra satellites.

Author information

Authors and Affiliations



M.J.M. wrote the manuscript with comments from all authors. J.C.A.M.-J. designed and analysed the VLA and VLBA observations. N.H.-W. and A.M.M.S. analysed the AMI-LA observations. J.-P.M. and J.C.A.M.-J. conducted the scintillation analysis. S.M., R.F. and M. Henze made significant contributions to the overall science case and manuscript. J.C., G.C.B. and M.G. provided support and analysis for the CARMA observations. The remaining authors either assisted with various aspects of the science case or are contributing members of the M 31 group.

Corresponding author

Correspondence to Matthew J. Middleton.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Methods, Supplementary References, Supplementary Tables 1-3 and Supplementary Figures 1-2. (PDF 412 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Middleton, M., Miller-Jones, J., Markoff, S. et al. Bright radio emission from an ultraluminous stellar-mass microquasar in M 31. Nature 493, 187–190 (2013).

Download citation

  • Received:

  • Accepted:

  • Published:

  • 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