The SCUBA-2 cosmology legacy survey: ALMA resolves the rest-frame far-infrared emission of sub-millemeter galaxies

Simpson, J. M.; Smail, Ian; Swinbank, A. M.; Almaini, O.; Blain, A. W.; Bremer, M. N.; Chapman, S. C.; Chen, Chian-Chou; Conselice, C.; Coppin, K. E. K.; Danielson, A. L. R.; Dunlop, J. S.; Edge, A. C.; Farrah, D.; Geach, J. E.; Hartley, W. G.; Ivison, R. J.; Karim, A.; Lani, C.; Ma, C.-J.; Meijerink, R.; Micha?owski, M. J.; Mortlock, A.; Scott, D.; Simpson, C. J.; Spaans, M.; Thomson, A. P.; van Kampen, E.; van der Werf, P. P.

Abstract

We present high-resolution (0’’.3) Atacama Large Millimeter Array 870 μm imaging of 52 sub-millimeter galaxies (SMGs) in the Ultra Deep Survey field to investigate the size and morphology of the sub-millimeter (sub-mm) emission on 2–10 kpc scales. We derive a median intrinsic angular size of FWHM = 0’’.30 ± 0’’.04 for the 23 SMGs in the sample detected at a signal-to-noise ratio (S/N) >10. Using the photometric redshifts of the SMGs we show that this corresponds to a median physical half-light diameter of 2.4 ±0.2 kpc. A stacking analysis of the SMGs detected at S/N < 10 shows they have sizes consistent with the 870 μm bright SMGs in the sample. We compare our results to the sizes of SMGs derived from other multi-wavelength studies, and show that the rest-frame ∼250 μm sizes of SMGs are consistent with studies of resolved 12CO (J = 3–2 to 7–6) emission lines, but that sizes derived from 1.4 GHz imaging appear to be approximately two times larger on average, which we attribute to cosmic ray diffusion. The rest-frame optical sizes of SMGs are around four times larger than the sub-millimeter sizes, indicating that the star formation in these galaxies is compact relative to the pre-existing stellar distribution. The size of the starburst region in SMGs is consistent with the majority of the star formation occurring in a central region, a few kiloparsecs in extent, with a median star formation rate surface density of 90 ± 30M_ yr−1 kpc−2, which may suggest that we are witnessing an intense period of bulge growth in these galaxies.

Citation

Simpson, J. M., Smail, I., Swinbank, A. M., Almaini, O., Blain, A. W., Bremer, M. N., …van der Werf, P. P. (2015). The SCUBA-2 cosmology legacy survey: ALMA resolves the rest-frame far-infrared emission of sub-millemeter galaxies. Astrophysical Journal, 799(1), 81. https://doi.org/10.1088/0004-637x/799/1/81

• Journal Article Type: Article
• Acceptance Date: Nov 15, 2014
• Online Publication Date: Jan 16, 2015
• Publication Date: Jan 16, 2015
• Deposit Date: Oct 6, 2017
• Publicly Available Date: Oct 6, 2017
• Journal: The Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 799
• Issue: 1
• Pages: 81
• DOI: https://doi.org/10.1088/0004-637x/799/1/81
• Public URL: https://nottingham-repository.worktribe.com/output/743086
• Publisher URL: http://iopscience.iop.org/article/10.1088/0004-637X/799/1/81/meta