SCUBA-2 Ultra Deep Imaging EAO Survey (Studies). III. Multiwavelength Properties, Luminosity Functions, and Preliminary Source Catalog of 450 μm Selected Galaxies

Lim, Chen-Fatt; Wang, Wei-Hao; Smail, Ian; Scott, Douglas; Chen, Chian-Chou; Chang, Yu-Yen; Simpson, James M.; Toba, Yoshiki; Shu, Xinwen; Clements, Dave; Greenslade, Josh; Ao, YiPing; Babul, Arif; Birkin, Jack; Chapman, Scott C.; Cheng, Tai-An; Cho, Brian S.; Dannerbauer, Helmut; Dudzevičiūtė, Ugnė; Dunlop, James; Gao, Yu; Goto, Tomotsugu; Ho, Luis C.; Hsu, Li-Ting; Hwang, Ho Seong; Jeong, Woong-Seob; Koprowski, Maciej; Lee, Chien-Hsiu; Lin, Ming-Yi; Lin, Wei-Ching; Michałowski, Michał J.; Parsons, Harriet; Sawicki, Marcin; Shirley, Raphael; Shim, Hyunjin; Urquhart, Sheona; Wang, Jianfa and Wang, Tao (2020). SCUBA-2 Ultra Deep Imaging EAO Survey (Studies). III. Multiwavelength Properties, Luminosity Functions, and Preliminary Source Catalog of 450 μm Selected Galaxies. The Astrophysical Journal, 889(2) p. 80.

DOI: https://doi.org/10.3847/1538-4357/ab607f

Abstract

We construct a SCUBA-2 450-μm map in the COSMOS field that covers an area of 300 arcmin $^2$ and reaches a 1σ noise level of 0.65 mJy in the deepest region. We extract 256 sources detected at 450 μm with signal-to-noise ratio > 4.0 and analyze the physical properties of their multi-wavelength counterparts. We find that most of the sources are at z≲3, with a median of z=1.79 $^{+0.03}_{-0.15}$ . About 35 $^{+32}_{-25}$ % of our sources are classified as starburst galaxies based on their total star-formation rates (SFRs) and stellar masses (M∗). By fitting the far-infrared spectral energy distributions, we find that our 450-μm-selected sample has a wide range of dust temperatures (20 K ≲T $_d$ ≲ 60 K), with a median of T $_d$ =38.3 $^{+0.4}_{-0.9}$ K. We do not find a redshift evolution in dust temperature for sources with L $_{IR}$ > 10¹² L $_\bigodot$ at z<3. However, we find a moderate correlation where dust temperature increases with the deviation from the SFR-M∗ relation. The increase in dust temperature also correlates with optical morphology, which is consistent with merger-triggered starbursts in sub-millimeter galaxies. Our galaxies do not show the tight IRX-βUV correlation that has been observed in the local Universe. We construct the infrared luminosity functions of our 450-μm sources and measure their comoving SFR densities. The contribution of the L $_{IR}$ > 10¹² L $_\bigodot$ population to the SFR density rises dramatically from z = 0 to 2 (∝ (1+z) $^{3.9\pm1.1}$ ) and dominates the total SFR density at z≳2.