Since their discovery, submillimetre-selected galaxies1,2 have revolutionized the field of galaxy formation and evolution. From the hundreds of square degrees mapped at submillimetre wavelengths3,4,5, only a handful of sources have been confirmed to lie at z > 5 (refs 6,7,8,9,10) and only two at z ≥ 6 (refs 11,12). All of these submillimetre galaxies are rare examples of extreme starburst galaxies with star formation rates of 1,000 M yr−1 and therefore are not representative of the general population of dusty star-forming galaxies. Consequently, our understanding of the nature of these sources, at the earliest epochs, is still incomplete. Here, we report the spectroscopic identification of a gravitationally amplified (μ = 9.3 ± 1.0) dusty star-forming galaxy at z = 6.027. After correcting for gravitational lensing, we derive an intrinsic less-extreme star formation rate of 380 ± 50 M yr−1 for this source and find that its gas and dust properties are similar to those measured for local ultra luminous infrared galaxies, extending the local trends to a poorly explored territory in the early Universe. The star-formation efficiency of this galaxy is similar to those measured in its local analogues13, despite a ~12 Gyr difference in cosmic time.

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We thank I. Smail for insightful comments that improved the quality of the paper. J.A.Z. acknowledges support from a Mexican Consejo Nacional de Ciencia y Tecnología studentship. R.J.I., L.D. and I.O. acknowledge support from the European Research Council in the form of the Advanced Investigator Programme, 321302, COSMICISM. L.D. additionally acknowledges support from the European Research Council Consolidator Grant CosmicDust. H.D. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness under the 2014 Ramón y Cajal programme MINECO RYC-2014-15686. M.J.M. acknowledges the support of the National Science Centre, Poland through the POLONEZ grant 2015/19/P/ST9/04010 and the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement number 665778. This work would not have been possible without long-term financial support from the Mexican Consejo Nacional de Ciencia y Tecnología during the construction and early operational phase of the Large Millimeter Telescope Alfonso Serrano, as well as support from the United States National Science Foundation via the University Radio Observatory programme, the Instituto Nacional de Astrofísica, Óptica y Electrónica and the University of Massachusetts. The SMA is a joint project between the Smithsonian Astrophysical Observatory and the Academia Sinica Institute of Astronomy and Astrophysics, and is funded by the Smithsonian Institution and the Academia Sinica. ALMA is a partnership of the European Southern Observatory (representing its member states), National Science Foundation (USA) and National Institutes of Natural Sciences (Japan), together with the National Research Council (Canada), Ministry of Science and Technology and Academia Sinica Institute of Astronomy and Astrophysics (Taiwan), and Korea Astronomy and Space Science Institute (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by the European Southern Observatory, Associated Universities/National Radio Astronomy Observatory and National Astronomical Observatory of Japan.

Author information


  1. Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro 1, 72840, Puebla, Mexico

    • Jorge A. Zavala
    • , David H. Hughes
    • , Itziar Aretxaga
    • , Miguel Chávez
    • , Daniel Rosa González
    • , David Sánchez-Argüelles
    • , Elena Terlevich
    • , Olga Vega
    • , Alan Villalba
    •  & Milagros Zeballos
  2. Department of Astronomy, The University of Texas at Austin, 2515 Speedway Boulevard, Austin, TX, 78712, USA

    • Jorge A. Zavala
  3. Consejo Nacional de Ciencia y Tecnología–Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro 1, 72840, Puebla, Mexico

    • Alfredo Montaña
    •  & Arturo I. Gómez-Ruiz
  4. Department of Astronomy, University of Massachusetts, Amherst, MA, 01003, USA

    • Min S. Yun
    • , Gopal Narayanan
    • , F. Peter Schloerb
    •  & Grant W. Wilson
  5. European Southern Observatory, Karl Schwarzschild Strasse 2, Garching bei München, 85748, Germany

    • R. J. Ivison
    •  & Ivan Oteo
  6. Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK

    • R. J. Ivison
    • , James S. Dunlop
    • , Loretta Dunne
    •  & Ivan Oteo
  7. School of Physics and Astronomy, Cardiff University, The Parade, Cardiff, CF24 3AA, UK

    • Elisabetta Valiante
    • , Stephen Eales
    • , Loretta Dunne
    •  & Matthew W. L. Smith
  8. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, 02138, USA

    • David Wilner
  9. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ, 85721, USA

    • Justin Spilker
  10. Instituto de Astronomía, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510, CDMX, Mexico

    • Vladimir Avila-Reese
  11. Department of Physics and Astronomy, University of California, Irvine, CA, 92697, USA

    • Asantha Cooray
    •  & Hooshang Nayyeri
  12. Instituto de Astrofísica de Canarias, E-38205, La Laguna, Tenerife, Spain

    • Helmut Dannerbauer
  13. Universidad de La Laguna, Departamento de Astrofísica, E-38206, La Laguna, Tenerife, Spain

    • Helmut Dannerbauer
  14. Astronomical Observatory Institute, Faculty of Physics, Adam Mickiewicz University, Słoneczna 36, 60-286, Poznań, Poland

    • Michał J. Michałowski
  15. Department of Physical Sciences, The Open University, Milton Keynes, MK7 6AA, UK

    • Stephen Serjeant
  16. Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA, Leiden, The Netherlands

    • Paul van der Werf


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J.A.Z. led the scientific analysis and the writing of the paper, as well as the SMA follow-up proposal. R.J.I., E.V., S.E., A.C., H.D., J.S.D., L.D., M.J.M., S.S., M.W.L.S. and P.v.d.W. contributed to the original Herschel proposals and observations, by which this source was discovered and catalogued. A.M., D.H.H., E.V., I.A., V.A.-R., M.C., D.R.G., E.T. and O.V. performed the selection of the sample for the LMT observations and led the LMT proposals. M.S.Y., G.N., F.P.S., G.W.W., D.S.-A., A.V. and M.Z. carried out LMT data reduction and interpretation. D.W., M.S.Y. and A.I.G.-R. assisted with the SMA observations and data reduction. J.S., I.O. and H.N. contributed to the data analysis and fitting and modelling the results. All the authors discussed and contributed to the writing of the paper.

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The authors declare no competing financial interests.

Corresponding author

Correspondence to Jorge A. Zavala.

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