Skip to main content

Thank you for visiting nature.com. 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 strong magnetic field around the supermassive black hole at the centre of the Galaxy

Nature volume 501, pages 391–394 (2013)Cite this article

Subjects

This article has been updated

Abstract

Earth’s nearest candidate supermassive black hole lies at the centre of the Milky Way1. Its electromagnetic emission is thought to be powered by radiatively inefficient accretion of gas from its environment2, which is a standard mode of energy supply for most galactic nuclei. X-ray measurements have already resolved a tenuous hot gas component from which the black hole can be fed3. The magnetization of the gas, however, which is a crucial parameter determining the structure of the accretion flow, remains unknown. Strong magnetic fields can influence the dynamics of accretion, remove angular momentum from the infalling gas4, expel matter through relativistic jets5 and lead to synchrotron emission such as that previously observed6,7,8. Here we report multi-frequency radio measurements of a newly discovered pulsar close to the Galactic Centre9,10,11,12 and show that the pulsar’s unusually large Faraday rotation (the rotation of the plane of polarization of the emission in the presence of an external magnetic field) indicates that there is a dynamically important magnetic field near the black hole. If this field is accreted down to the event horizon it provides enough magnetic flux to explain the observed emission—from radio to X-ray wavelengths—from the black hole.

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

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

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

Figure 1: Average pulse profiles of PSR J1745–2900 at each of the radio frequencies where detections have been made.
Figure 2: Pulse profile of PSR J1745–2900 at 8.35 GHz.
Figure 3: RM synthesis analysis for the radio polarization of PSR J1745–2900.

Similar content being viewed by others

Change history

  • 20 August 2013

    Source Data files for Figs 1–3 were added.

References

  1. Genzel, R., Eisenhauer, F. & Gillessen, S. The Galactic Center massive black hole and nuclear star cluster. Rev. Mod. Phys. 82, 3121–3195 (2010)

    Article  ADS  CAS  Google Scholar 

  2. Narayan, R. & Yi, I. Advection-dominated accretion: a self-similar solution. Astrophys. J. 428, L13–L16 (1994)

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  4. Balbus, S. A. & Hawley, J. F. A powerful local shear instability in weakly magnetized disks. I - Linear analysis. II - Nonlinear evolution. Astrophys. J. 376, 214–233 (1991)

    Article  ADS  Google Scholar 

  5. Beckwith, K., Hawley, J. F. & Krolik, J. H. The influence of magnetic field geometry on the evolution of black hole accretion flows: similar disks, drastically different jets. Astrophys. J. 678, 1180–1199 (2008)

    Article  ADS  Google Scholar 

  6. Falcke, H. & Markoff, S. The jet model for Sgr A*: radio and X-ray spectrum. Astron. Astrophys. 362, 113–118 (2000)

    ADS  Google Scholar 

  7. Mościbrodzka, M., Gammie, C. F., Dolence, J. C., Shiokawa, H. & Leung, P. K. Radiative Models of Sgr A* from GRMHD simulations. Astrophys. J. 706, 497–507 (2009)

    Article  ADS  Google Scholar 

  8. Dexter, J., Agol, E., Fragile, P. C. & McKinney, J. C. The submillimeter bump in Sgr A* from relativistic MHD simulations. Astrophys. J. 717, 1092–1104 (2010)

    Article  ADS  Google Scholar 

  9. Kennea, J. A. et al. Swift Discovery of a new soft gamma repeater, SGR J1745–29, near Sagittarius A*. Astrophys. J. 770, L24 (2013)

    Article  ADS  Google Scholar 

  10. Mori, K. et al. NuSTAR discovery of a 3.76 s transient magnetar near Sagittarius A*. Astrophys. J. 770, L23 (2013)

    Article  ADS  Google Scholar 

  11. Eatough, R. P. et al. Detection of radio pulsations from the direction of the NuSTAR 3.76 second X-ray pulsar at 8.35 GHz. Astron. Telegr. 5040, 1 (2013)

    ADS  Google Scholar 

  12. Shannon, R. M. & Johnston, S. Radio properties of the magnetar near Sagittarius A* from observations with the Australia Telescope Compact Array. Preprint at http://arxiv.org/abs/1305.3036 (2013)

  13. Bower, G. C., Falcke, H., Wright, M. C. & Backer, D. C. Variable linear polarization from Sagittarius A*: evidence of a hot turbulent accretion flow. Astrophys. J. 618, L29–L32 (2005)

    Article  ADS  Google Scholar 

  14. Marrone, D. P., Moran, J. M., Zhao, J.-H. & Rao, R. An unambiguous detection of Faraday rotation in Sagittarius A*. Astrophys. J. 654, L57–L60 (2007)

    Article  ADS  Google Scholar 

  15. Liu, K., Wex, N., Kramer, M., Cordes, J. M. & Lazio, T. J. W. Prospects for probing the spacetime of Sgr A* with pulsars. Astrophys. J. 747, 1 (2012)

    Article  ADS  Google Scholar 

  16. Wharton, R. S., Chatterjee, S., Cordes, J. M., Deneva, J. S. & Lazio, T. J. W. Multiwavelength constraints on pulsar populations in the Galactic Center. Astrophys. J. 753, 108 (2012)

    Article  ADS  Google Scholar 

  17. Eatough, R. P. et al. in Neutron Stars and Pulsars: Challenges and Opportunities After 80 Years (ed. Leeuwen, J. V. ) 382–384 (Cambridge Univ. Press, 2013)

  18. Lazio, T. J. W. & Cordes, J. M. Hyperstrong radio-wave scattering in the Galactic Center. II. A likelihood analysis of free electrons in the Galactic Center. Astrophys. J. 505, 715–731 (1998)

    Article  ADS  Google Scholar 

  19. Rea, N. et al. Chandra localization of the soft gamma repeater in the Galactic Center region. Astron. Telegr. 5032, 1 (2013)

    ADS  Google Scholar 

  20. Cordes, J. M. & Lazio, T. J. W. NE2001.I. A new model for the galactic distribution of free electrons and its fluctuations. Preprint at http://arxiv.org/abs/astroph/0207156 (2002)

  21. Lazarus, P., Kaspi, V. M., Champion, D. J., Hessels, J. W. T. & Dib, R. Constraining radio emission from magnetars. Astrophys. J. 744, 97 (2012)

    Article  ADS  Google Scholar 

  22. Lee, K. J. et al. Polarisation profiles and rotation measure of PSR J1745–2900 measured at Effelsberg. Astron. Telegr. 5064, 1 (2013)

    ADS  Google Scholar 

  23. Brentjens, M. A. & de Bruyn, A. G. Faraday rotation measure synthesis. Astron. Astrophys. 441, 1217–1228 (2005)

    Article  ADS  Google Scholar 

  24. Law, C. J., Brentjens, M. A. & Novak, G. A constraint on the organization of the Galactic Center magnetic field using Faraday rotation. Astrophys. J. 731, 36 (2011)

    Article  ADS  Google Scholar 

  25. Bower, G. C., Backer, D. C., Zhao, J.-H., Goss, M. & Falcke, H. The linear polarization of Sagittarius A*. I. VLA spectropolarimetry at 4.8 and 8.4 GHz. Astrophys. J. 521, 582–586 (1999)

    Article  ADS  Google Scholar 

  26. Zhao, J.-H. et al. The high-density ionized gas in the central parsec of the Galaxy. Astrophys. J. 723, 1097–1109 (2010)

    Article  ADS  CAS  Google Scholar 

  27. Plante, R. L., Lo, K. Y. & Crutcher, R. M. The magnetic fields in the galactic center: detection of H1 Zeeman splitting. Astrophys. J. 445, L113–L116 (1995)

    Article  ADS  CAS  Google Scholar 

  28. Muno, M. P. et al. Diffuse X-ray emission in a deep Chandra image of the Galactic Center. Astrophys. J. 613, 326–342 (2004)

    Article  ADS  CAS  Google Scholar 

  29. Macquart, J.-P., Bower, G. C., Wright, M. C. H., Backer, D. C. & Falcke, H. The rotation measure and 3.5 millimeter polarization of Sagittarius A*. Astrophys. J. 646, L111–L114 (2006)

    Article  ADS  Google Scholar 

  30. Falcke, H., Mannheim, K. & Biermann, P. L. The galactic center radio jet. Astron. Astrophys. 278, L1–L4 (1993)

    ADS  Google Scholar 

Download references

Acknowledgements

We wish to thank D. D. Xu., P. Lazarus and L. Guillemot for discussions. We also thank O. Wucknitz and R. Beck for reading the manuscript. R.K., L.G.S. and P.C.C.F. gratefully acknowledge financial support from the European Research Council for the ERC Starting Grant BEACON under contract no. 279702. K.J.L. was funded by ERC Advanced Grant LEAP under contract no. 227947. H.F. acknowledges funding from an Advanced Grant of the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement no. 227610. This work was based on observations with the 100-m telescope of the MPIfR (Max-Planck-Institut für Radioastronomie) at Effelsberg. The Nançay radio telescope is part of the Paris Observatory, associated with the Centre National de la Recherche Scientifique (CNRS), and partly supported by the Région Centre in France. The National Radio Astronomy Observatory (NRAO) is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Author information

Authors and Affiliations

  1. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany,

    R. P. Eatough, H. Falcke, R. Karuppusamy, K. J. Lee, D. J. Champion, G. Desvignes, D. H. F. M. Schnitzeler, L. G. Spitler, M. Kramer, B. Klein, A. Brunthaler, P. C. C. Freire, A. Kraus, A. Noutsos & N. Wex

  2. Department of Astrophysics, Institute for Mathematics, Astrophysics and Particle Physics, Radboud University, PO Box 9010, 6500 GL Nijmegen, The Netherlands,

    H. Falcke

  3. ASTRON, PO Box 2, 7990 AA Dwingeloo, The Netherlands,

    H. Falcke & A. T. Deller

  4. Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, UK,

    E. F. Keane, M. Kramer, C. Bassa, A. G. Lyne & B. Stappers

  5. Bonn-Rhein-Sieg University of Applied Sciences, Grantham-Allee 20, D-53757 Sankt Augustin, Germany,

    B. Klein

  6. Astronomy Department, B-20 Hearst Field Annex, University of California, Berkeley, 94720-3411, California, USA

    G. C. Bower

  7. LPC2E/CNRS - Université d’Orléans, 45071 Orléans, France,

    I. Cognard

  8. Nançay/Paris Observatory, 18330 Nançay, France,

    I. Cognard

  9. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, 22903, Virginia, USA

    P. B. Demorest

Authors
  1. R. P. Eatough
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. H. Falcke
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. R. Karuppusamy
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. K. J. Lee
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. D. J. Champion
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. E. F. Keane
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. G. Desvignes
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. D. H. F. M. Schnitzeler
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. L. G. Spitler
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. M. Kramer
    View author publications

    You can also search for this author in PubMed Google Scholar

  11. B. Klein
    View author publications

    You can also search for this author in PubMed Google Scholar

  12. C. Bassa
    View author publications

    You can also search for this author in PubMed Google Scholar

  13. G. C. Bower
    View author publications

    You can also search for this author in PubMed Google Scholar

  14. A. Brunthaler
    View author publications

    You can also search for this author in PubMed Google Scholar

  15. I. Cognard
    View author publications

    You can also search for this author in PubMed Google Scholar

  16. A. T. Deller
    View author publications

    You can also search for this author in PubMed Google Scholar

  17. P. B. Demorest
    View author publications

    You can also search for this author in PubMed Google Scholar

  18. P. C. C. Freire
    View author publications

    You can also search for this author in PubMed Google Scholar

  19. A. Kraus
    View author publications

    You can also search for this author in PubMed Google Scholar

  20. A. G. Lyne
    View author publications

    You can also search for this author in PubMed Google Scholar

  21. A. Noutsos
    View author publications

    You can also search for this author in PubMed Google Scholar

  22. B. Stappers
    View author publications

    You can also search for this author in PubMed Google Scholar

  23. N. Wex
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

R.P.E.: initial detections, observations performed at Effelsberg and data processing; H.F.: observational and theoretical background and paper formulation; R.K.: observational technical assistance and pulsar timing; K.J.L.: polarization and RM measurements; D.J.C.: pulsar timing solution; E.F.K.: flux density calculations, observational assistance and observations at Jodrell Bank; G.D.: observations at Nançay; D.H.F.M.S.: observational background and RM interpretation; L.G.S.: observational background and data processing and analysis; M.K.: observational background and RM interpretation; B.K.: technical observational assistance at Effelsberg; C.B.: observations at Jodrell Bank; G.C.B.: observations at the VLA and RM interpretation; A.B.: observations at the VLA; I.C.: observations at Nançay; A.T.D.: observations at the VLA; P.B.D.: observations at the VLA; P.C.C.F.: observational background and pulsar timing; A.K.: technical observational assistance at Effelsberg; A.G.L.: observations at Jodrell Bank and help with initial detections; A.N.: observational background and RM interpretation; B.S.: observations at Jodrell Bank; N.W.: theoretical background and orbital characteristics.

Corresponding author

Correspondence to R. P. Eatough.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

PowerPoint slides

Source data

Rights and permissions

Reprints and permissions

About this article

Cite this article

Eatough, R., Falcke, H., Karuppusamy, R. et al. A strong magnetic field around the supermassive black hole at the centre of the Galaxy. Nature 501, 391–394 (2013). https://doi.org/10.1038/nature12499

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature12499

This article is cited by

Comments

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.

Search

Advanced search

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