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.

Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre


Recent measurements of stellar orbits1,2,3 provide compelling evidence that the compact radio source Sagittarius A* (refs 4, 5) at the Galactic Centre is a 3.6-million-solar-mass black hole. Sgr A* is remarkably faint in all wavebands other than the radio region6,7, however, which challenges current theories of matter accretion and radiation surrounding black holes8. The black hole's rotation rate is not known, and therefore neither is the structure of space-time around it. Here we report high-resolution infrared observations of Sgr A* that reveal ‘quiescent’ emission and several flares. The infrared emission originates from within a few milliarcseconds of the black hole, and traces very energetic electrons or moderately hot gas within the innermost accretion region. Two flares exhibit a 17-minute quasi-periodic variability. If the periodicity arises from relativistic modulation of orbiting gas, the emission must come from just outside the event horizon, and the black hole must be rotating at about half of the maximum possible rate.

This is a preview of subscription content

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Detection of variable near-infrared emission from SgrA*.
Figure 2: Light curves of the SgrA* infrared flares and quiescent emission in 2002–03.
Figure 3: Spectral energy distribution emission from SgrA*.


  1. 1

    Schödel, R. et al. A star in a 15.2 year orbit around the supermassive black hole at the centre of the Milky Way. Nature 419, 694–696 (2002)

    ADS  Article  Google Scholar 

  2. 2

    Ghez, A. M. et al. The first measurement of spectral lines in a short-period star bound to the Galaxy's central black hole: A paradox of youth. Astrophys. J. 586, L127–L131 (2003)

    ADS  CAS  Article  Google Scholar 

  3. 3

    Eisenhauer, F. et al. A geometric determination of the distance to the Galactic Center. Astrophys. J. Lett. (in the press); preprint at 〈〉 (2003)

  4. 4

    Doeleman, S. S. et al. Structure of SgrA* at 86 GHz using VLBI closure quantities. Astron. J. 121, 2610–2617 (2001)

    ADS  Article  Google Scholar 

  5. 5

    Backer, D. C. & Sramek, R. A. Proper motion of the compact, nonthermal radio source in the Galactic Center, SgrA*. Astrophys. J. 524, 805–815 (1999)

    ADS  Article  Google Scholar 

  6. 6

    Baganoff, F. K. et al. Chandra X-ray spectroscopic imaging of SgrA* and the central parsec of the Galaxy. Astrophys. J. 591, 891–915 (2003)

    ADS  Article  Google Scholar 

  7. 7

    Hornstein, S. D. et al. Limits on the short-term variability of SgrA* in the near-IR. Astrophys. J. 577, L9–L13 (2002)

    ADS  Article  Google Scholar 

  8. 8

    Melia, F. & Falcke, H. The supermassive black hole at the Galactic Center. Annu. Rev. Astron. Astrophys. 39, 309–352 (2001)

    ADS  CAS  Article  Google Scholar 

  9. 9

    Lenzen, R., Hofmann, R., Bizenberger, P. & Tusche, A. CONICA: The high-resolution near-infrared camera for the ESO VLT. Proc. SPIE 3354 (IR Astronomical Instrumentation), 606–614 (1998)

    ADS  CAS  Article  Google Scholar 

  10. 10

    Rousset, G. et al. Design of the Nasmyth adaptive optics system (NAOS) of the VLT. Proc. SPIE 3353 (Adaptive Optics Technology), 508–516 (1998)

    ADS  Article  Google Scholar 

  11. 11

    Benlloch, S., Wilms, J., Edelson, R., Raqoob, T. & Staubert, T. Quasi-periodic oscillation in Seyfert galaxies: Significance levels. The case of Mrk 766. Astrophys. J. 562, L121–L124 (2001)

    ADS  Article  Google Scholar 

  12. 12

    Ghez, A. M. et al. Variable infrared emission from the supermassive black hole at the center of the Milky Way. Astrophys. J. Lett. (submitted); preprint at 〈〉 (2003)

  13. 13

    Baganoff, F. K. Multi-wavelength monitoring of SgrA* during Chandra observations of multiple X-ray flares. High Energy Astrophysics Division (HEAD) AAS Abstr. 3.02, 35 (2003)

  14. 14

    Alexander, T. & Sternberg, A. Near-IR microlensing of stars by the supermassive black hole in the Galactic Center. Astrophys. J. 520, 137–148 (1999)

    ADS  Article  Google Scholar 

  15. 15

    Yuan, F., Markoff, S. & Falcke, H. A jet-ADAF model for SgrA*. Astron. Astrophys. 854, 854–863 (2002)

    ADS  Article  Google Scholar 

  16. 16

    Liu, S. & Melia, F. New constraints on the nature of the radio emission in SgrA*. Astrophys. J. 561, L77–L80 (2001)

    ADS  Article  Google Scholar 

  17. 17

    Yuan, F., Quataert, E. & Narayan, R. Nonthermal electrons in radiatively inefficient flow models of SgrA*. Astrophys. J. (submitted); preprint at 〈〉 (2003)

  18. 18

    Markoff, S., Falcke, H., Yuan, F. & Biermann, P. L. The nature of the 10ksec X-ray flare in SgrA*. Astron. Astrophys. 379, L13–L16 (2001)

    ADS  Article  Google Scholar 

  19. 19

    Baganoff, F. K. et al. Rapid X-ray flaring from the direction of the supermassive black hole at the Galactic Centre. Nature 413, 45–48 (2001)

    ADS  CAS  Article  Google Scholar 

  20. 20

    Porquet, D. et al. XMM-Newton observation of the brightest X-ray flare detected so far from SgrA*. Astron. Astrophys. 407, L17–L20 (2003)

    ADS  Article  Google Scholar 

  21. 21

    Zhao, J.-H. et al. Variability of SgrA*: Flares at 1 mm. Astrophys. J. 586, L29–L32 (2003)

    ADS  Article  Google Scholar 

  22. 22

    Miyazaki, A., Tstsumi, T. & Tsuboi, M. Flares of SgrA* at short submm wavelengths. Astron. Nachr. 324, 3–9 (2003)

    Article  Google Scholar 

  23. 23

    Nayakshin, S., Cuadra, J. & Sunyaev, R. X-ray flares from SgrA*: Star-disk interactions? Astron. Astrophys. (in the press); preprint at 〈〉 (2003)

  24. 24

    Hollywood, J. M. & Melia, F. General relativistic effects on the infrared spectrum of thin accretion disks in active galactic nuclei: Application to SgrA*. Astrophys. J. Suppl. 112, 423–455 (1997)

    ADS  Article  Google Scholar 

  25. 25

    Bardeen, J. M., Press, W. M. & Teukolsky, S. A. Rotating black holes: Locally non-rotating frames, energy extraction and scalar synchrotron radiation. Astrophys. J. 178, 347–369 (1972)

    ADS  Article  Google Scholar 

  26. 26

    Melia, F., Bromley, C., Liu, S. & Walker, C. K. Measuring the black hole spin in SgrA*. Astrophys. J. 554, L37–L40 (2001)

    ADS  Article  Google Scholar 

  27. 27

    De Villiers, J.-P., Hawley, J. F. & Krolik, J. H. Magnetically driven accretion flows in the Kerr metric I: Models and overall structure. Astrophys. J. (submitted); preprint at 〈〉 (2003)

  28. 28

    Nowak, M. A., Wagoner, R. V., Begelman, M. C. & Lehr, D. E. The 67 Hz feature in the black hole candidate GRS1915 + 105 as a possible diskoseismic mode. Astrophys. J. 477, L91–L94 (1997)

    ADS  Article  Google Scholar 

  29. 29

    Bardeen, J. M. & Pettersen, J. A. The Lense-Thirring effect and accretion disks around Kerr black holes. Astrophys. J. 105, L65–L67 (1975)

    ADS  Article  Google Scholar 

Download references


This Letter is based on observations at the VLT of the European Observatory (ESO) in Chile. We thank the teams who developed and constructed the near-infrared camera CONICA and the AO system NAOS, and especially their principal investigators, R. Lenzen, R. Hofmann and G. Rousset. We thank H. Falcke and S. Markoff for access to their database of the SgrA* SED, as well as discussions of emission processes. We are grateful to D. Porquet and P. Predehl for discussions of their XMM data, S. Nayakshin, M. Rees, R. Sunyaev and especially E. Quataert for discussions of accretion disk physics, and A. Sternberg for suggestions on the paper.

Author information



Corresponding author

Correspondence to R. Genzel.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Genzel, R., Schödel, R., Ott, T. et al. Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre. Nature 425, 934–937 (2003).

Download citation

Further reading


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