2013MNRAS.432...53G

The first deep blank-field 450 µm map (1σ ~ 1.3 mJy) from the Submillimetre Common-User Bolometer Array-2 SCUBA-2 Cosmology Legacy Survey (S2CLS), conducted with the James Clerk Maxwell Telescope (JCMT) is presented. Our map covers 140 arcmin2 of the Cosmological Evolution Survey field, in the footprint of the Hubble Space Telescope (HST) Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey. Using 60 submillimetre galaxies detected at ≥ 3.75σ, we evaluate the number counts of 450-µm-selected galaxies with flux densities S450 > 5 mJy. The 8 arcsec JCMT beam and high sensitivity of SCUBA-2 now make it possible to directly resolve a larger fraction of the cosmic infrared background (CIB, peaking at λ ∼ 200 µm) into the individual galaxies responsible for its emission than has previously been possible at this wavelength. At S450 > 5 mJy, we resolve (7.4±0.7)x10-2 MJy sr-1 of the CIB at 450 µm (equivalent to 16±7 percent of the absolute brightness measured by the Cosmic Background Explorer at this wavelength) into point sources. A further ∼ 40 percent of the CIB can be recovered through a statistical stack of 24 µm emitters in this field, indicating that the majority (~60 percent) of the CIB at 450 µm is emitted by galaxies with S450 > 2 mJy. The average redshift of 450 µm emitters identified with an optical/near-infrared counterpart is estimated to be <z> = 1.3, implying that the galaxies in the sample are in the ultraluminous class (L_IR~1.1×10^12 L_☉). If the galaxies contributing to the statistical stack lie at similar redshifts, then the majority of the CIB at 450 µm is emitted by galaxies in the luminous infrared galaxy (LIRG) class with LIR > 3.6x1011L☉.