Red, redder, reddest: SCUBA-2 imaging of colour-selected Herschel sources

S. Duivenvoorden*, S. Oliver, J. M. Scudder, J. Greenslade, D. A. Riechers, S. M. Wilkins, V. Buat, S. C. Chapman, D. L. Clements, A. Cooray, K. E.K. Coppin, H. Dannerbauer, G. De Zotti, J. S. Dunlop, S. A. Eales, A. Efstathiou, D. Farrah, J. E. Geach, W. S. Holland, P. D. HurleyR. J. Ivison, L. Marchetti, G. Petitpas, M. T. Sargent, D. Scott, M. Symeonidis, M. Vaccari, J. D. Vieira, L. Wang, J. Wardlow, M. Zemcov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


High-redshift, luminous, dusty star-forming galaxies (DSFGs) constrain the extremity of galaxy formation theories. The most extreme are discovered through follow-up on candidates in large area surveys. Here, we present extensive 850 μm SCUBA-2 follow-up observations of 188 red DSFG candidates from the Herschel Multitiered Extragalactic Survey (HerMES) LargeMode Survey, covering 274 deg2.We detected 87 per cent with a signal-to-noise ratio > 3 at 850 μm. We introduce a new method for incorporating the confusion noise in our spectral energy distribution fitting by sampling correlated flux density fluctuations from a confusion limited map. The new 850 μm data provide a better constraint on the photometric redshifts of the candidates, with photometric redshift errors decreasing from σz/(1 + z) ≈ 0.21 to 0.15. Comparison spectroscopic redshifts also found little bias (〈(z-zspec)/(1+zspec)〉 = 0.08). The mean photometric redshift is found to be 3.6 with a dispersion of 0.4 and we identify 21 DSFGs with a high probability of lying at z > 4. After simulating our selection effects we find number counts are consistent with phenomenological galaxy evolution models. There is a statistically significant excess of WISE-1 and SDSS sources near our red galaxies, giving a strong indication that lensing may explain some of the apparently extreme objects. Nevertheless, our sample includes examples of galaxies with the highest star formation rates in the Universe (≫103 M yr-1).

Original languageEnglish
Pages (from-to)1099-1119
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
Early online date15 Mar 2018
Publication statusPublished - 11 Jun 2018


  • Galaxies: High-redshift
  • Galaxies: Starburst
  • Infrared: Galaxies
  • Submillimetre: Galaxies


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