The SCUBA-2 Cosmology Legacy Survey: Multi-wavelength Properties of ALMA-identified Submillimeter Galaxies in UKIDSS UDS

Simpson, J.M.; Smail, I.; Swinbank, A.M.; Ivison, R.J.; Dunlop, J.S.; Geach, J.E.; Almaini, O.; Arumugam, V.; Bremer, M.N.; Chen, C.-C.; Conselice, C.; Coppin, K.E.K.; Farrah, D.; Ibar, E.; Hartley, W.G.; Ma, C.J.; Michałowski, M.J.; Scott, D.; Spaans, M.; Thomson, A.P.; van der Werf, P.P.

Abstract

We present a multi-wavelength analysis of 52 submillimeter galaxies (SMGs), identified using ALMA 870 μm continuum imaging in a pilot program to precisely locate bright SCUBA-2-selected submillimeter sources in the UKIDSS Ultra Deep Survey (UDS) field. Using the available deep (especially near-infrared) panoramic imaging of the UDS field at optical-to-radio wavelengths we characterize key properties of the SMG population. The median photometric redshift of the bright ALMA/SCUBA-2 UDS (AS2UDS) SMGs that are detected in a sufficient number of wavebands to derive a robust photometric redshift is z = 2.65 ± 0.13. However, similar to previous studies, 27% of the SMGs are too faint at optical-to-near-infrared wavelengths to derive a reliable photometric redshift. Assuming that these SMGs lie at z gsim 3 raises the median redshift of the full sample to z = 2.9 ± 0.2. A subset of 23 unlensed, bright AS2UDS SMGs have sizes measured from resolved imaging of their rest-frame far-infrared emission. We show that the extent and luminosity of the far-infrared emission are consistent with the dust emission arising from regions that are, on average, optically thick at a wavelength of ${\lambda }_{0}\geqslant 75\,\mu {\rm{m}}$ (1σ dispersion of 55–90 μm). Using the dust masses derived from our optically thick spectral energy distribution models, we determine that these galaxies have a median hydrogen column density of N H = 9.8${}_{-0.7}^{+1.4}$ × 1023 cm−2, or a corresponding median V-band obscuration of A v = 540${}_{-40}^{+80}$ mag, averaged along the line of sight to the source of their rest-frame ~200 μm emission. We discuss the implications of this extreme attenuation by dust for the multi-wavelength study of dusty starbursts and reddening-sensitive tracers of star formation.

Citation

Simpson, J., Smail, I., Swinbank, A., Ivison, R., Dunlop, J., Geach, J., …van der Werf, P. (2017). The SCUBA-2 Cosmology Legacy Survey: Multi-wavelength Properties of ALMA-identified Submillimeter Galaxies in UKIDSS UDS. Astrophysical Journal, 839(1), Article 58. https://doi.org/10.3847/1538-4357/aa65d0

• Journal Article Type: Article
• Acceptance Date: Feb 19, 2017
• Online Publication Date: Apr 13, 2017
• Publication Date: Apr 13, 2017
• Deposit Date: May 18, 2017
• Publicly Available Date: May 31, 2017
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 839
• Issue: 1
• Article Number: 58
• DOI: https://doi.org/10.3847/1538-4357/aa65d0
• Public URL: https://durham-repository.worktribe.com/output/1358793
• Related Public URLs: https://arxiv.org/abs/1611.03084