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Published May 20, 2019 | Published + Accepted Version
Journal Article Open

The IRAM/GISMO 2 mm Survey in the COSMOS Field

Abstract

We present deep continuum observations at a wavelength of 2 mm centered on the COSMOS field using the Goddard IRAM Superconducting Millimeter Observer (GISMO) at the IRAM 30 m telescope. These data constitute the widest deep 2 mm survey to date, reaching a uniform σ ~ 0.23 mJy beam−1 sensitivity over ~250 arcmin^2 at ~24'' resolution. We detect four sources at high significance (S/N ≥ 4.4) with an expected number of false detections of 0.09 sources and five sources at 4.4 > S/N ≥ 3.7 with an expected number of false detections of 1.65 sources. Combined with deep GISMO observations in GOODS-N, we constrain the 2 mm number counts over one decade in flux density. These measurements agree with most galaxy evolution models tested here, except those with a large population of dusty star-forming galaxies at z > 7. Five GISMO sources have counterparts in (sub)millimeter catalogs available in COSMOS. Their redshifts suggest that all but one lie above z ~ 3. These four high-redshift (z > 3) galaxies have z = 3.9, SFRs ~ 400–1200 M ⊙ yr^(−1), and M_(dust) ~ 10^(9.5) M⊙. They provide a relatively complete selection (~66%) of the most luminous (L_(IR) > 10^(12.6) L⊙) and highest-redshift (z > 3) galaxies detected within our survey area by AzTEC at 1.1 mm. We thus conclude that 2 mm surveys favor the selection of massive, vigorously star-forming, high-redshift galaxies. This is corroborated by GISMO-C4, a source with a low false-detection probability (~6.2%), for which the absence of a (sub)millimeter counterpart supports a high-redshift origin (z ≳ 3).

Additional Information

© 2019 The American Astronomical Society. Received 2019 February 1; revised 2019 April 9; accepted 2019 April 13; published 2019 May 23. Based on observations with the IRAM 30 m telescope. We would like to thank the referee for comments that have helped improve the paper. B.M., A.K., E.J.A., and F.B. acknowledge support from the Collaborative Research Centre 956, subproject A1, funded by the Deutsche Forschungsgemeinschaft (DFG). We would like to thank Carsten Kramer, Santiago Navarro, David John, Albrecht Sievers, and the entire IRAM Granada staff for their support during the instrument installation and observations. C.M.C. thanks the University of Texas at Austin College of Natural Sciences and NSF grants AST-1714528 and AST-1814034 for support. D.R. acknowledges support from the National Science Foundation under grant No. AST-1614213. Based on observations carried out under project Nos. 247-11, 227-12, 242-13, 117-14, and 232-15 with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). This work was also supported through NSF ATI grants 1020981 and 1106284. Facility: IRAM: 30 m. -

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Published - Magnelli_2019_ApJ_877_45.pdf

Accepted Version - 1904.10006.pdf

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August 19, 2023
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