Volume 577, May 2015
|Number of page(s)||32|
|Published online||27 April 2015|
(Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies
Department of PhysicsUniversity of Zagreb,
Bijenička cesta 32,
2 Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército 441, Santiago, Chile
3 Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
4 Spitzer Science Center, 314-6 Caltech, Pasadena, CA 91125, USA
5 Astronomy Department, Cornell University, 220 Space Sciences Building, Ithaca, NY 14853, USA
6 Institut d’Astrophysique de Paris, UMR7095 CNRS, Université Pierre et Marie Curie, 98 bis Boulevard Arago, 75014 Paris, France
7 Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
8 Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, Domaine Universitaire, 38406, Saint Martin d’Hères, France
9 Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
10 23 rue d’Yerres, 91230 Montgeron, France
11 National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719, USA
12 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching bei München, Germany
13 Institute for Astronomy, University of Hawaii, 2680 Woddlawn Drive, Honolulu, HI 96822, USA
14 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
15 National Radio Astronomy Observatory/NAASC, 520 Edgemont Road, Charlottesville, VA 22903, USA
Received: 19 September 2014
Accepted: 13 February 2015
We used the Plateau de Bure Interferometer (PdBI) to map a sample of 15 submillimetre galaxies (SMGs) in the COSMOS field at the wavelength of 1.3 mm. The target SMGs were originally discovered in the James Clerk Maxwell Telescope (JCMT)/AzTEC 1.1 mm continuum survey at S/N1.1 mm = 4−4.5. This paper presents, for the first time, interferometric millimetre-wavelength observations of these sources. The angular resolution of our observations, ~1''̣8, allowed us to accurately determine the positions of the target SMGs. Using a detection threshold of S/N1.3 mm> 4.5 regardless of multiwavelength counterpart association, and 4 <S/N1.3 mm ≤ 4.5 if a multiwavelength counterpart within 1''̣5 is also present, the total number of detections in our survey is 22. The most significant PdBI detection of S/N1.3 mm = 10.3 is towards AzTEC19. Three of our detected SMGs (AzTEC21, 27, and 28; which corresponds to 20%) are marginally resolved at our angular resolution, and these sources are found to have elongated or clumpy morphologies and/or multiple components. Using optical to near-infrared photometric redshifts, available spectroscopic redshifts, and redshifts estimated from the radio-to-submm spectral index we infer a median redshift of = 3.20 ± 0.25 for our sample. To study the overall multiplicity and redshift distribution of flux-limited samples of SMGs we combined these sources with the 15 brightest JCMT/AzTEC SMGs detected at 1.1 mm, AzTEC1−15, and studied previously. This constitutes a complete, flux- and S/N-limited 1.1-mm selected sample. We find that the median redshift for the 15 brightest JCMT/AzTEC SMGs (= 3.05 ± 0.44) is consistent with that for AzTEC16−30. This conforms to recent observational findings that SMGs do not exhibit any significant trend between the redshift and (sub)mm flux density. For the combined AzTEC1−30 sample we derive a median redshift of = 3.17 ± 0.27, consistent with previous results based on mm-selected samples. We further infer that within the combined AzTEC1−30 sample ~25 ± 9% of sources separate into multiple components.
Key words: galaxies: evolution / galaxies: formation / galaxies: starburst / galaxies: star formation / submillimeter: galaxies
Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).
Appendices are available in electronic form at http://www.aanda.org
© ESO, 2015
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