Journal Article

AzTEC millimetre survey of the COSMOS field – III. Source catalogue over 0.72 deg<sup>2</sup> and plausible boosting by large-scale structure

I. Aretxaga, G. W. Wilson, E. Aguilar, S. Alberts, K. S. Scott, N. Scoville, M. S. Yun, J. Austermann, T. P. Downes, H. Ezawa, B. Hatsukade, D. H. Hughes, R. Kawabe, K. Kohno, T. Oshima, T. A. Perera, Y. Tamura and M. Zeballos

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 415, issue 4, pages 3831-3850
Published in print August 2011 | ISSN: 0035-8711
Published online August 2011 | e-ISSN: 1365-2966 | DOI:
AzTEC millimetre survey of the COSMOS field – III. Source catalogue over 0.72 deg2 and plausible boosting by large-scale structure

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We present a 0.72 deg2 contiguous 1.1-mm survey in the central area of the Cosmological Evolution Survey field carried out to a 1σ≈ 1.26 mJy beam−1 depth with the AzTEC camera mounted on the 10-m Atacama Submillimeter Telescope Experiment. We have uncovered 189 candidate sources at a signal-to-noise ratio (S/N) ≥ 3.5, out of which 129, with S/N ≥ 4, can be considered to have little chance of being spurious (≲2 per cent). We present the number counts derived with this survey, which show a significant excess of sources when compared to the number counts derived from the ∼0.5 deg2 area sampled at similar depths in the Submillimetre Common-User Bolometer Array (SCUBA) HAlf Degree Extragalactic Survey (SHADES). They are, however, consistent with those derived from fields that were considered too small to characterize the overall blank-field population. We identify differences to be more significant in the S1.1mm≳ 5 mJy regime, and demonstrate that these excesses in number counts are related to the areas where galaxies at redshifts z≲ 1.1 are more densely clustered. The positions of optical–infrared galaxies in the redshift interval 0.6 ≲z≲ 0.75 are the ones that show the strongest correlation with the positions of the 1.1-mm bright population (S1.1mm≳ 5 mJy), a result which does not depend exclusively on the presence of rich clusters within the survey sampled area. The most likely explanation for the observed excess in number counts at 1.1-mm is galaxy–galaxy and galaxy–group lensing at moderate amplification levels, which increases in amplitude as one samples larger and larger flux densities. This effect should also be detectable in other high-redshift populations.

Keywords: surveys; galaxies: evolution; cosmology: miscellaneous; submillimetre: galaxies

Journal Article.  11005 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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