An overview of current progress in the SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES) project

Chen-Fatt Lim^1,2*, Wei-Hao Wang¹, Yu-Yen Chang¹

¹Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), Academia Sinica Institute, Taipei, Taiwan
²Graduate Institute of Astrophysics, National Taiwan University (NTU), Taipei, Taiwan

* Presenter:Chen-Fatt Lim, email:d04244001@ntu.edu.tw

The majority of star formation in the Universe is obscured by dust and produces strong infrared and sub-millimeter radiation. Far-infrared or sub-millimeter observations are therefore required to fully understand the formation history of galaxies. In the past two decades, sub-millimeter surveys have revealed a population of dusty galaxies (sub-millimeter galaxies, SMGs) at z ~ 1–3.5, occupying the same epoch as the peak of quasar activities. SMGs dominate the massive end of star-formation with star formation rates of > 100 M_⦿ yr^-1 and reside in massive dark matter halos (10¹² to 10¹³ h^-1 M_⦿), suggesting that SMGs may be the progenitors of elliptical galaxies in the local Universe. However, our understanding of this population is still incomplete, especially at the faint end.
In this talk, I will review the progress and results of the SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES) project. STUDIES is a JCMT Large Project aiming at obtaining confusion limited 450 μm images in the COSMOS and SXDS regions, to detect the majority of the dusty galaxy population. So far, ~ 60% of the total allocated integration of the COSMOS field has been obtained. This leads to by far the deepest 450 μm image with an area of ~600 arcmin2 and a noise level of ~ 0.65 mJy in the map center, which is ~ 10× deeper than the deepest Herschel images at similar wavebands. The source counts from our first-year data are consistent with previous works and show no evidence of a faint-end termination or turn-over of the counts. We conducted SED fitting on sources with multi-wavelength counterparts to estimate their physical properties, including photometric redshifts, infrared luminosities, star formation rates, dust temperatures, stellar masses, and dust attenuations. Because of the unprecedented depth of the STUDIES image, these analyses reached ~ 30 M_⦿ yr^-1 galaxies at z ~ 2. We also investigated the stellar morphology of our 450 μm sources at z < 3 by using Hubble Space Telescope near-infrared observations. We are now building a 450 μm-based machine-learning algorithm to identify the SMG candidates in the entire 1.77 deg² COSMOS region. There will be roughly 9300 such machine-learning candidates and they will be used for clustering analyses and halo mass estimations for faint SMGs. All the above will advance our understanding of the typical members in the high-redshift dusty galaxy population.

Keywords: high redshift galaxies, sub-millimeter galaxies, dusty galaxies, galaxy evolution