Volume 548, December 2012
|Number of page(s)||34|
|Published online||13 November 2012|
ESO ALMA COFUND Fellow
2 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
3 Argelander-Institute for Astronomy, Auf dem Hügel 71, Bonn, 53121, Germany
4 University of Zagreb, Physics Department, Bijenička cesta 32, 10002 Zagreb, Croatia
5 European Southern Observatory, Alonso de Córdoba 3107, Vitacura, Casilla 19001, Santiago 19, Chile
6 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
7 Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
8 California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125, USA
9 IRAM, 300 rue de la piscine, 38406 Saint-Martin d’Hères, France
10 Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany
11 Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu CNRS Université Paris Diderot, CE-Saclay, pt courrier 131, 91191 Gif-sur-Yvette, France
12 Institut d’Astrophysique de Paris, UMR 7095 CNRS, Université Pierre et Marie Curie, 98bis boulevard Arago, 75014 Paris, France
13 National Radio Astronomy Observatory, PO Box 0, Socorro, NM 87801-0387, USA
14 INAF – Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy
15 Harvard-Smithsonian Centre for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
16 Laboratoire d’Astrophysique de Marseille, Université de Provence, CNRS, BP 8, Traverse du Siphon, 13376 Marseille Cedex 12, France
17 National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719, USA
18 Institute for Astronomy, ETH Zürich, Wolfgang-Pauli-strasse 27, 8093 Zürich, Switzerland
19 Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI, 96822, USA
20 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
21 Research Center for Space and Cosmic Evolution, Ehime University, Bunkyo-cho, Matsuyama 790-8577, Japan
Received: 8 April 2012
Accepted: 24 May 2012
We present new IRAM Plateau de Bure interferometer (PdBI) 1.3 mm continuum observations at ~1.5′′ resolution of 28 submillimeter galaxies (SMGs), previously discovered with the 870 μm bolometer LABOCA at the APEX telescope from the central 0.7 deg2 of the COSMOS field. Nineteen out of the 28 LABOCA sources were detected with PdBI at a ≳3σ level of ≈1.4 mJy/beam. A combined analysis of this new sample with existing interferometrically identified SMGs in the COSMOS field yields the following results: i) ≳15%, and possibly up to ~40% of single-dish detected SMGs consist of multiple sources; ii) statistical analysis of multi-wavelength counterparts to single-dish SMGs shows that only ~50% have real radio or IR counterparts; iii) ~18% of interferometric SMGs have either no multi-wavelength counterpart or only a radio-counterpart; and iv) ~50–70% of z ≳ 3 SMGs have no radio counterparts (down to an rms of 7–12 μJy at 1.4 GHz). Using the exactinterferometric positions to identify the multi-wavelength counterparts allows us to determine accurate photometric redshifts for these sources. The redshift distributions of the combined and the individual 1.1 mm and 870 μm selected samples shows a higher mean and a broader width than those derived in previous studies. This study finds that on average brighter and/or mm- selected SMGs are located at higher redshifts, consistent with previous studies. The mean redshift for the 1.1 mm selected sample ( = 3.1 ± 0.4) is tentatively higher than that for the 870 μm selected sample ( = 2.6 ± 0.4). Based on our nearly complete sample of AzTEC 1.1 mm SMGs in a 0.15 deg2 area, we infer a higher surface density of z ≳ 4 SMGs than predicted by current cosmological models. In summary, our findings imply that interferometric identifications at (sub-)millimeter wavelengths are crucial to build statistically complete and unbiased samples of SMGs.
Key words: surveys / galaxies: starburst / galaxies: fundamental parameters / galaxies: high-redshift / galaxies: statistics / 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, 2012
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