The SCUBA Half Degree Extragalactic Survey - IV. Radio-mm-FIR photometric redshifts
Abstract
We present the redshift distribution of the Submillimetre Common-User Bolometer Array (SCUBA) Half Degree Survey (SHADES) galaxy population based on the rest-frame radio-mm-far-infrared (FIR) colours of 120 robustly detected 850 μm sources in the Lockman Hole East (LH) and Subaru XMM-Newton Deep Field (SXDF). The redshift distribution derived from the full spectral energy distribution (SED) information is shown to be narrower than that determined from the radio-sub-mm spectral index, as more photometric bands contribute to a higher redshift accuracy. The redshift distribution of sources derived from at least two photometric bands peaks at z ~ 2.4 and has a near-Gaussian distribution, with 50 per cent (interquartile range) of sources at z = 1.8-3.1. We find a statistically significant difference between the measured redshift distributions in the two fields; the SXDF peaking at a slightly lower redshift (median z ~ 2.2) than the LH (median z ~ 2.7), which we attribute to the noise properties of the radio observations. We demonstrate, however, that there could also be field-to-field variations that are consistent with the measured differences in the redshift distributions and, hence, that the incomplete area observed by SHADES with SCUBA, despite being the largest sub-mm survey to date, may still be too small to fully characterize the bright sub-mm galaxy population. Finally, we present a brief comparison with the predicted, or assumed, redshift distributions of sub-mm galaxy formation and evolution models, and we derive the contribution of these SHADES sources and the general sub-mm galaxy population to the star formation rate density at different epochs.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- August 2007
- DOI:
- 10.1111/j.1365-2966.2007.12036.x
- arXiv:
- arXiv:astro-ph/0702503
- Bibcode:
- 2007MNRAS.379.1571A
- Keywords:
-
- surveys;
- galaxies: evolution;
- cosmology: miscellaneous;
- infrared: galaxies;
- submillimetre;
- Astrophysics
- E-Print:
- MNRAS, accepted (22 pages, 9 figures, 5 tables). Revised version, minor modifications and 2 extra figures