paper

SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES). V. Confusion-limited Submillimeter Galaxy Number Counts at 450 m and Data Release for the COSMOS Field

arXiv:2405.20616 · doi:10.3847/1538-4357/ad53c1

Abstract

We present confusion-limited SCUBA-2 450-m observations in the COSMOS-CANDELS region as part of the JCMT Large Program, SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES). Our maps at 450 and 850 m cover an area of 450 arcmin. We achieved instrumental noise levels of 0.59 mJy beam and 0.09 mJy beam in the deepest area of each map. The corresponding confusion noise levels are estimated to be 0.65 and 0.36 mJy beam. Above the 4 (3.5) threshold, we detected 360 (479) sources at 450 m and 237 (314) sources at 850 m. We derive the deepest blank-field number counts at 450 m, covering the flux-density range of 2 to 43 mJy. These are in agreement with other SCUBA-2 blank-field and lensing-cluster observations, but are lower than various model counts. We compare the counts with those in other fields and find that the field-to-field variance observed at 450 m at the scale is consistent with Poisson noise, so there is no evidence of strong 2-D clustering at this scale. Additionally, we derive the integrated surface brightness at 450 m down to 2.1 mJy to be ~Jy deg, contributing to (414)\% of the 450-m extragalactic background light (EBL) measured by COBE and Planck. Our results suggest that the 450-m EBL may be fully resolved at ~mJy, which extremely deep lensing-cluster observations and next-generation submillimeter instruments with large aperture sizes may be able to achieve.

29 pages, 14 figures, accepted for publication in ApJ

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