IRAM 30m-EMIR Redshift Search of z = 3 − 4 Lensed Dusty Starbursts selected from the HerBS sample

Abstract Using the EMIR instrument on the IRAM 30 m telescope, we conducted a spectroscopic redshift search of seven zphot ∼ 4 sub-millimetre bright galaxies selected from the Herschel Bright Sources (HerBS) sample with fluxes at 500 μm greater than 80 mJy. For four sources, we obtained spectroscopic redshifts between 3.4 < z < 4.1 through the detection of multiple CO-spectral lines with J ≥3. Later, we detected low-J transitions for two of these sources with the GBT including the CO(1-0) transition. For the remaining three sources, more data are needed to determine the spectroscopic redshift unambiguously. The measured CO luminosities and line widths suggest that all these sources are gravitationally lensed. These observations demonstrate that the 2 mm window is indispensable to confirm robust spectroscopic redshifts for z < 4 sources. Finally, we present an efficient graphical method to correctly identify spectroscopic redshifts

JINGLE, a JCMT legacy survey of dust and gas for galaxy evolution studies: II. SCUBA-2 850 μm data reduction and dust flux density catalogues

We present the SCUBA-2 850μm component of JINGLE, the new JCMT large survey for dust and gas in nearby galaxies, which with 193 galaxies is the largest targeted survey of nearby galaxies at 850 μm. We provide details of our SCUBA-2 data reduction pipeline, optimized for slightly extended sources, and including a calibration model adjusted to match conventions used in other far-infrared (FIR) data. We measure total integrated fluxes for the entire JINGLE sample in 10 infrared/submillimetre bands, including all WISE, Herschel-PACS, Herschel-SPIRE, and SCUBA-2 850 μm maps, statistically accounting for the contamination by CO(J = 3-2) in the 850 μm band. Of our initial sample of 193 galaxies, 191 are detected at 250 μm with a ≥5σ significance. In the SCUBA-2 850 μm band we detect 126 galaxies with ≥3σ significance. The distribution of the JINGLE galaxies in FIR/sub-millimetre colour-colour plots reveals that the sample is not well fit by single modified-blackbody models that assume a single dust-emissivity index (β). Instead, our new 850 μm data suggest either that a large fraction of our objects require β < 1.5, or that a model allowing for an excess of sub-mm emission (e.g. a broken dust emissivity law, or a very cold dust component ≲10 K) is required. We provide relations to convert FIR colours to dust temperature and β for JINGLE-like galaxies. For JINGLE the FIR colours correlate more strongly with star-formation rate surface-density rather than the stellar surface-density, suggesting heating of dust is greater due to younger rather than older stellar-populations, consistent with the low proportion of early-type galaxies in the sample

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

We present confusion-limited SCUBA-2 450 μm observations in the COSMOS-CANDELS region as part of the James Clerk Maxwell Telescope Large Program SCUBA-2 Ultra Deep Imaging EAO Survey. Our maps at 450 and 850 μm cover an area of 450 arcmin2. 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 4σ (3.5σ) 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 2–43 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 2D clustering at this scale. Additionally, we derive the integrated surface brightness at 450 μm down to 2.1 mJy to be 57.3−6.2+1.0 Jy deg−2, contributing to 41% ± 4% of the 450 μm extragalactic background light (EBL) measured by Cosmic Background Explorer and Planck. Our results suggest that the 450 μm EBL may be fully resolved at 0.08−0.08+0.09 mJy, which extremely deep lensing-cluster observations and next-generation submillimeter instruments with large aperture sizes may be able to achieve