HerMES: ALMA imaging of Herschel-selected dusty star-forming galaxies

Journal Article · Sat Oct 10 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/812/1/43· OSTI ID:22882498

Bussmann, R. S.; Riechers, D. ^[1]; Fialkov, A. ^[2]; Scudder, J.; Oliver, S. J. ^[3]; Hayward, C. C. ^[4]; Cowley, W. I.; Lacey, C. ^[5]; Bock, J. ^[6]; Calanog, J.; Cooray, A.; De Bernardis, F. ^[7]; Chapman, S. C. ^[8]; Farrah, D. ^[9]; Fu, Hai ^[10]; Gavazzi, R. ^[11]; Hopwood, R. ^[12]; Ivison, R. J. ^[13]; Jarvis, M. ^[14]; Loeb, A. ^[15] ; others, and

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1. Department of Astronomy, Space Science Building, Cornell University, Ithaca, NY 14853-6801 (United States)
2. Departement de Physique, Ecole Normale Superieure, CNRS, 24 rue Lhomond, F-75005, Paris (France)
3. Astronomy Centre, Dept. of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom)
4. TAPIR 350-17, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125 (United States)
5. Institute for Computational Cosmology, Department of Physics, University of Durham, South Road, Durham DH1 3LE (United Kingdom)
6. California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States)
7. Dept. of Physics and Astronomy, University of California, Irvine, CA 92697 (United States)
8. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
9. Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States)
10. Department of Physics and Astronomy, The University of Iowa, 203 Van Allen Hall, Iowa City, IA 52242 (United States)
11. Institut d’Astrophysique de Paris, UMR 7095, CNRS, UPMC Univ. Paris 06, 98bis boulevard Arago, F-75014, Paris (France)
12. Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)
13. UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
14. Department of Astrophysics, Denys Wilkinson Building, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom)
15. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

The Herschel Multi-tiered Extragalactic Survey (HerMES) has identified large numbers of dusty star-forming galaxies (DSFGs) over a wide range in redshift. A detailed understanding of these DSFGs is hampered by the limited spatial resolution of Herschel. We present 870 μm 0.″45 resolution imaging obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) of a sample of 29 HerMES DSFGs that have far-infrared (FIR) flux densities that lie between the brightest of sources found by Herschel and fainter DSFGs found via ground-based surveys in the submillimeter region. The ALMA imaging reveals that these DSFGs comprise a total of 62 sources (down to the 5σ point-source sensitivity limit in our ALMA sample; σ≈0.2 mJy). Optical or near-infrared imaging indicates that 36 of the ALMA sources experience a significant flux boost from gravitational lensing (μ>1.1), but only six are strongly lensed and show multiple images. We introduce and make use of uvmcmcfit, a general-purpose and publicly available Markov chain Monte Carlo visibility-plane analysis tool to analyze the source properties. Combined with our previous work on brighter Herschel sources, the lens models presented here tentatively favor intrinsic number counts for DSFGs with a break near 8 mJy at 880 μm and a steep fall-off at higher flux densities. Nearly 70% of the Herschel sources break down into multiple ALMA counterparts, consistent with previous research indicating that the multiplicity rate is high in bright sources discovered in single-dish submillimeter or FIR surveys. The ALMA counterparts to our Herschel targets are located significantly closer to each other than ALMA counterparts to sources found in the LABOCA ECDFS Submillimeter Survey. Theoretical models underpredict the excess number of sources with small separations seen in our ALMA sample. The high multiplicity rate and small projected separations between sources seen in our sample argue in favor of interactions and mergers plausibly driving both the prodigious emission from the brightest DSFGs as well as the sharp downturn above S{sub 880}=8 mJy.

• OSTI ID: 22882498
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 812; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMIC DUST
EMISSION
FLUX DENSITY
GALACTIC EVOLUTION
GALAXIES
GRAVITATIONAL LENSES
INTERACTIONS
MARKOV PROCESS
MONTE CARLO METHOD
MULTIPLICITY
POINT SOURCES
RED SHIFT
SENSITIVITY
SPATIAL RESOLUTION
STAR EVOLUTION
STARS