THE SCUBA-2 COSMOLOGY LEGACY SURVEY: ALMA RESOLVES THE REST-FRAME FAR-INFRARED EMISSION OF SUB-MILLIMETER GALAXIES

Journal Article · Tue Jan 20 00:00:00 EST 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/799/1/81· OSTI ID:22364465

Simpson, J. M.; Smail, Ian; Swinbank, A. M.; Chen, Chian-Chou; Danielson, A. L. R.; Edge, A. C.; Ma, C. -J. ^[1]; Almaini, O.; Conselice, C.; Hartley, W. G.; Lani, C. ^[2]; Blain, A. W. ^[3]; Bremer, M. N.; Coppin, K. E. K. ^[4]; Chapman, S. C. ^[5]; Dunlop, J. S.; Ivison, R. J. ^[6]; Farrah, D. ^[7]; Geach, J. E. ^[8]; others, and

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1. Institute for Computational Cosmology, Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom)
2. School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)
3. Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)
4. School of Physics, HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom)
5. Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 3J5 (Canada)
6. Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford HIll, Edinburgh EH9 3HJ (United Kingdom)
7. Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States)
8. Centre for Astrophysics Research, Science and Technology Research Institute, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom)

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 {sup 12}CO (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 ± 30 M {sub ☉} yr{sup –1} kpc{sup –2}, which may suggest that we are witnessing an intense period of bulge growth in these galaxies.

• OSTI ID: 22364465
• Journal Information: Astrophysical Journal, Vol. 799, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
APPROXIMATIONS
CARBON 12
CARBON MONOXIDE
COMPARATIVE EVALUATIONS
COSMIC RADIATION
COSMOLOGY
DENSITY
DIFFUSION
EMISSION SPECTRA
GALAXIES
GHZ RANGE
RED SHIFT
SIGNAL-TO-NOISE RATIO
STARS
VISIBLE RADIATION