(Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. I. Multiwavelength identifications and redshift distribution

Miettinen, Oscari and Smolčić, Vernesa and Novak, Mario and Aravena, M. and Karim, A. and Masters, D. and Riechers, D. A. and Bussmann, R. S. and McCraken, H. J. and Ilbert, O. and Bertoldi, F. and Capak, P. and Feruglio, C. and Halliday, C. and Kartaltepe, J. S. and Navarrete, F. and Salvato, M. and Sanders, D. and Schinnerer, E. and Sheth, K. (2015) (Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. I. Multiwavelength identifications and redshift distribution. Astronomy and Astrophysics, 577. Art. No. A29. ISSN 0004-6361

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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/N_(1.1 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/N_(1.3 mm)> 4.5 regardless of multiwavelength counterpart association, and 4 <S/N_(1.3 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/N_(1.3 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 z = 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 (z = 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 z = 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.

Item Type: Article
Keywords: galaxies: evolution – galaxies: formation – galaxies: starburst – galaxies: star formation – submillimeter: galaxies
Date: 27 April 2015
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: © 2015 ESO. Article published by EDP Sciences. Received 19 September 2014. Accepted 13 February 2015. Published online: 27 April 2015.
Divisions: Faculty of Science > Department of Physics
Publisher: EDP Sciences
Depositing User: Vernesa Smolčić
Date Deposited: 08 May 2016 20:22
Last Modified: 09 May 2016 18:54
URI: http://digre.pmf.unizg.hr/id/eprint/4808

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