Swinbank, A. M., Smail, I., Longmore, S., Harris, A. I., Baker, A. J., de Breuck, C., Richard, J., Edge, A. C., Ivison, R. J., Blundell, Raymond, Coppin, K. E. K., Cox, P., Gurwell, Mark A., Hainline, L. J., Krips, M., Lundgren, A., Neri, R., Siana, B., Siringo, G., Stark, D. P., Wilner, David J., and Younger, J. D. 2010. "Intense star formation within resolved compact regions in a galaxy at z = 2.3." Nature, 464 733–736. https://doi.org/10.1038/nature08880.
Massive galaxies in the early Universe have been shown to be forming stars at surprisingly high rates. 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 (Msolar) per year. These intense bursts of star formation are believed to be driven by mergers between gas-rich galaxies. 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 100parsecs. 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.
