SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES). V. Confusion-limited Submillimeter Galaxy Number Counts at 450 μm and Data Release for the COSMOS Field
The Astrophysical Journal(2024)
Abstract
We present confusion-limited SCUBA-2 450-μm 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 μm cover an area of
450 arcmin^2. We achieved instrumental noise levels of
σ_450= 0.59 mJy beam^-1 and σ_850= 0.09
mJy beam^-1 in the deepest area of each map. The corresponding confusion
noise levels are estimated to be 0.65 and 0.36 mJy beam^-1. Above the 4
(3.5) σ threshold, we detected 360 (479) sources at 450 μm and 237
(314) sources at 850 μm. We derive the deepest blank-field number counts at
450 μm, 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 μm at the
R=6^' 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 μm down to 2.1 mJy to be 57.3^+1.0_-6.2 Jy
deg^-2, contributing to (41±4)% of the 450-μm extragalactic
background light (EBL) measured by COBE and Planck. Our results suggest that
the 450-μm EBL may be fully resolved at 0.08^+0.09_-0.08 mJy, which
extremely deep lensing-cluster observations and next-generation submillimeter
instruments with large aperture sizes may be able to achieve.
MoreTranslated text
Key words
Catalogs,Cosmic background radiation,Galaxy evolution,High-redshift galaxies,Submillimeter astronomy
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