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.

Intense star formation within resolved compact regions in a galaxy at z = 2.3


Massive galaxies in the early Universe have been shown to be forming stars at surprisingly high rates1,2,3. Prominent examples are dust-obscured galaxies which are luminous when observed at sub-millimetre wavelengths and which may be forming stars at a rate of 1,000 solar masses (M) per year4,5,6,7. These intense bursts of star formation are believed to be driven by mergers between gas-rich galaxies8,9. Probing the properties of individual star-forming regions within these galaxies, however, is beyond the spatial resolution and sensitivity of even the largest telescopes at present. Here we report observations of the sub-millimetre galaxy SMMJ2135-0102 at redshift z = 2.3259, which has been gravitationally magnified by a factor of 32 by a massive foreground galaxy cluster lens. This magnification, when combined with high-resolution sub-millimetre imaging, resolves the star-forming regions at a linear scale of only 100 parsecs. We find that the luminosity densities of these star-forming regions are comparable to the dense cores of giant molecular clouds in the local Universe, but they are about a hundred times larger and 107 times more luminous. Although vigorously star-forming, the underlying physics of the star-formation processes at z ≈ 2 appears to be similar to that seen in local galaxies, although the energetics are unlike anything found in the present-day Universe.

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: Multi-wavelength images of the galaxy cluster MACSJ2135-0102.
Figure 2: Carbon monoxide observations of SMMJ2135-0102 obtained with the Green Bank Telescope and Plateau de Bure Interferometer.
Figure 3: Spectral energy distribution of the lensed galaxy.
Figure 4: Relation between size and luminosity of star forming regions.


  1. Chapman, S. C. et al. A redshift survey of the submillimeter galaxy population. Astrophys. J. 622, 772–796 (2005)

    Article  ADS  CAS  Google Scholar 

  2. Genzel, R. et al. The rapid formation of a large rotating disk galaxy three billion years after the Big Bang. Nature 442, 786–796 (2006)

    Article  ADS  CAS  Google Scholar 

  3. Coppin, K. et al. The SCUBA Half Degree Extragalactic Survey—VI. 350-μm mapping of submillimetre galaxies. Mon. Not. R. Astron. Soc. 384, 1597–1610 (2008)

    Article  ADS  CAS  Google Scholar 

  4. Smail, I. et al. A deep sub-millimeter survey of lensing clusters: a new window on galaxy formation and evolution. Astrophys. J. 490, 5–8 (1997)

    Article  ADS  Google Scholar 

  5. Hughes, D. H. et al. High-redshift star formation in the Hubble Deep Field revealed by a submillimetre-wavelength survey. Nature 394, 241–247 (1998)

    Article  ADS  CAS  Google Scholar 

  6. Blain, A. W. et al. Submillimeter galaxies. Phys. Rep. 369, 111–176 (2002)

    Article  ADS  Google Scholar 

  7. Lilly, S. J. et al. The Canada-United Kingdom deep submillimeter survey. II. First identifications, redshifts, and implications for galaxy evolution. Astrophys. J. 518, 641–655 (1999)

    Article  ADS  Google Scholar 

  8. Swinbank, A. M. et al. The link between submillimetre galaxies and luminous ellipticals: near-infrared IFU spectroscopy of submillimetre galaxies. Mon. Not. R. Astron. Soc. 371, 465–476 (2006)

    Article  ADS  CAS  Google Scholar 

  9. Tacconi, L. J. et al. Submillimeter galaxies at z 2: evidence for major mergers and constraints on lifetimes, IMF, and CO-H2 conversion factor. Astrophys. J. 680, 246–262 (2008)

    Article  ADS  CAS  Google Scholar 

  10. Yun, M. S. et al. Spitzer IRAC infrared colours of submillimetre-bright. Mon. Not. R. Astron. Soc. 389, 333–340 (2008)

    Article  ADS  CAS  Google Scholar 

  11. Greve, T. R. et al. An interferometric CO survey of luminous submillimetre galaxies. Mon. Not. R. Astron. Soc. 359, 1165–1183 (2005)

    Article  ADS  CAS  Google Scholar 

  12. Solomon, P. M. & Vanden Bout, P. A. Molecular gas at high redshift. Annu. Rev. Astron. Astrophys. 43, 677–725 (2005)

    Article  ADS  CAS  Google Scholar 

  13. Bruzual, G. & Charlot, S. Stellar population synthesis at the resolution of 2003. Mon. Not. R. Astron. Soc. 344, 1000–1028 (2003)

    Article  ADS  Google Scholar 

  14. Chapman, S. C. et al. A median redshift of 2.4 for galaxies bright at submillimetre wavelengths. Nature 422, 695–698 (2003)

    Article  ADS  CAS  Google Scholar 

  15. Kennicutt, R. Star formation in galaxies along the Hubble sequence. Annu. Rev. Astron. Astrophys. 36, 189–232 (1998)

    Article  ADS  CAS  Google Scholar 

  16. Elmegreen, B. G. Galactic bulge formation as a maximum intensity starburst. Astrophys. J. 517, 103–107 (1999)

    Article  ADS  Google Scholar 

  17. Gao, Y. & Solomon, P. M. HCN survey of normal spiral, infrared-luminous, and ultraluminous galaxies. Astrophys. J. (Suppl.) 152, 63–80 (2004)

    Article  ADS  CAS  Google Scholar 

  18. Walter, F. et al. A kiloparsec-scale hyper-starburst in a quasar host less than 1 gigayear after the Big Bang. Nature 457, 699–701 (2009)

    Article  ADS  CAS  Google Scholar 

  19. Scoville, N. Z. et al. The far-infrared luminosity of molecular clouds in the Galaxy. Astrophys. J. 339, 149–162 (1989)

    Article  ADS  CAS  Google Scholar 

  20. Downes, D. et al. New observations and a new interpretation of CO(3–2) in IRAS F10214+4724. Astrophys. J. 453, L65–L68 (1995)

    Article  ADS  CAS  Google Scholar 

  21. Snell, R. et al. Molecular clouds and infrared stellar clusters in the far outer galaxy. Astrophys. J. 578, 229–244 (2002)

    Article  ADS  Google Scholar 

  22. Caldwell, D. A. et al. Star formation activity in the Large Magellanic Cloud: far-infrared emission from IRAS high-resolution data. Astrophys. J. 472, 611–623 (1996)

    Article  ADS  CAS  Google Scholar 

  23. Livanou, E. et al. Star-burst regions in the LMC. Astron. Astrophys. 451, 431–434 (2006)

    Article  ADS  CAS  Google Scholar 

  24. Hill, T. et al. Millimetre continuum observations of southern massive star formation regions—I. SIMBA observations of cold cores. Mon. Not. R. Astron. Soc. 363, 405–451 (2005)

    Article  ADS  CAS  Google Scholar 

  25. Lintott, C. et al. Hot cores: probes of high-redshift galaxies? Mon. Not. R. Astron. Soc. 360, 1527–1531 (2002)

    Article  ADS  Google Scholar 

  26. Carilli, C. et al. High-resolution imaging of molecular line emission from high-redshift QSOs. Astrophys. J. 123, 1838–1846 (2002)

    CAS  Google Scholar 

  27. Sakamoto, K. et al. Submillimeter array imaging of the CO(3–2) line and 860μm continuum of Arp 220: tracing the spatial distribution of luminosity. Astrophys. J. 684, 957–977 (2008)

    Article  ADS  CAS  Google Scholar 

  28. Harris, A. I. et al. The Zpectrometer: an ultra-wideband spectrometer for the green bank telescope. Astron. Soc. Pacif. Conf. Ser. 375, 82–93 (2007)

    ADS  CAS  Google Scholar 

Download references


We thank the staff at Green Bank Telescope for scheduling the Zpectrometer observations at short notice, and the ESO director for granting director’s discretionary time observations with SABOCA. A.M.S. gratefully acknowledges a Royal Astronomical Society Sir Norman Lockyer Fellowship, and J.R. and D.P.S. acknowledge a Marie Curie fellowship and a Science Technology and Facilities Council fellowship respectively. J.D.Y. acknowledges support from NASA through a Hubble Fellowship. The Zpectrometer observations were carried out on the Robert C. Byrd Green Bank Telescope, which is operated by the National Radio Astronomy Observatory, a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The APEX observations were carried out with ESO Telescopes. The 870 μm interferometric observations were carried out with the Sub-Millimeter Array, which 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. The CO(3-2) observations were carried out with the Plateau de Bure Interferometer, which is supported by INSU/CNRS (France), Max Planck Gesellschaft (MPG; Germany), and Instituto Geográfico Nacional (IGN; Spain). J. D. Y. is a Hubble Fellow.

Author Contributions A.M.S., I.S., R.J.I. and A.C.E. designed and proposed the observations, collected the data and performed the multi-wavelength analysis. A.I.H., A.J.B. and L.J.H. conducted the Green Bank Telescope/Zpectrometer observations and reduced and analysed the data. C.D.B, A.L. and G.S. carried out the LABOCA and SABOCA observations and wrote a data-reduction pipeline. B.S. proposed and reduced the mid-infrared Spitzer observations. K.E.K.C. carried out the far-infrared spectral energy distribution fitting. S.L., R.B., M.G., D.W. and J.D.Y. conducted the Sub-Millimeter Array observations and reduced the data. P.C., M.K. and R.N carried out the Plateau de Bure Interferometer observations and reduced the data. J.R. constructed the gravitational lensing model. D.P.S. carried out the optical/near-infrared spectral energy distribution modelling. All co-authors discussed the results and commented on the manuscript.

Author information

Authors and Affiliations


Corresponding author

Correspondence to A. M. Swinbank.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains (1) Observations and Data Reduction; (2) Gravitational Lens Modelling; (3) Spectral Energy Distribution Analysis; (4) Size and Luminosity of Star-forming Regions; and Additional References. (PDF 257 kb)

PowerPoint slides

Rights and permissions

Reprints and permissions

About this article

Cite this article

Swinbank, A., Smail, I., Longmore, S. et al. Intense star formation within resolved compact regions in a galaxy at z = 2.3. Nature 464, 733–736 (2010).

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