A SCUBA/Spitzer investigation of the far-infrared extragalactic background

S. Dye, S. A. Eales, M. L.N. Ashby, J. S. Huang, E. Egami, M. Brodwin, S. Lilly, T. Webb

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


We have measured the contribution of submillimetre and mid-infrared sources to the extragalactic background radiation at 70 and 160 μm. Specifically, we have stacked flux in 70- and 160-μm Spitzer Space Telescope (Spitzer) observations of the Canada-United Kingdom Deep Submillimetre Survey 14-h field at the positions of 850-μm sources detected by SCUBA and also 8- and 24-μm sources detected by Spitzer. We find that per source, the SCUBA galaxies are the strongest and the 8-μm sources the weakest contributors to the background flux at both 70 and 160 μm. Our estimate of the contribution of the SCUBA sources is higher than previous estimates. However, expressed as a total contribution, the full 8-μm source catalogue accounts for twice the total 24-μm source contribution and ∼10 times the total SCUBA source contribution. The 8-μm sources account for the majority of the background radiation at 160 μm with a flux of 0.87 ± 0.16 MJy sr-1 and at least a third at 70 μm with a flux of 0.103 ± 0.019 MJy sr -1. These measurements are consistent with current lower limits on the background at 70 and 160 μm. Finally, we have investigated the 70- and 160-μm emission from the 8- and 24-μm sources as a function of redshift. We find that the average 70-μm flux per 24-μm source and the average 160-μm flux per 8- and 24-μm source is constant over all red-shifts, up to z ∼ 4. In contrast, the low-redshift half (z < 1) of the of 8-μm sample contributes approximately four times the total 70-μm flux of the high-redshift half. These trends can be explained by a single non-evolving SED.

Original languageEnglish (US)
Pages (from-to)725-734
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
StatePublished - Feb 2007


  • Infrared: galaxies
  • Submillimetre

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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