The first deep blank-field 450 \mu m map ( 1 \sigma \approx 1.3 mJy ) from the SCUBA–2 Cosmology Legacy Survey ( S2CLS ) , conducted with the James Clerk Maxwell Telescope ( JCMT ) is presented .
Our map covers 140 arcmin ^ { 2 } of the Cosmological Evolution Survey ( COSMOS ) field , in the footprint of the Hubble Space Telescope ( HST ) Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey ( CANDELS ) .
Using 60 submillimetre galaxies ( SMGs ) detected at \geq 3.75 \sigma , we evaluate the number counts of 450 \mu m-selected galaxies with flux densities S _ { 450 } > 5 mJy .
The 8 ^ { \prime \prime } 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 \lambda \sim 200 \mu m ) into the individual galaxies responsible for its emission than has previously been possible at this wavelength .
At S _ { 450 } > 5 mJy we resolve ( 7.4 \pm 0.7 ) \times 10 ^ { -2 } MJy sr ^ { -1 } of the CIB at 450 \mu m ( equivalent to 16 \pm 7 % of the absolute brightness measured by the Cosmic Background Explorer at this wavelength ) into point sources .
A further \sim 40 % of the CIB can be recovered through a statistical stack of 24 \mu m emitters in this field , indicating that the majority ( \approx 60 % ) of the CIB at 450 \mu m is emitted by galaxies with S _ { 450 } > 2 mJy .
The average redshift of 450 \mu m emitters identified with an optical/near-infrared counterpart is estimated to be \langle z \rangle = 1.3 , implying that the galaxies in the sample are in the ultraluminous class ( L _ { IR } \approx 1.1 \times 10 ^ { 12 } { L _ { \odot } } ) .
If the galaxies contributing to the statistical stack lie at similar redshifts , then the majority of the CIB at 450 \mu m is emitted by galaxies in the LIRG class with L _ { IR } > 3.6 \times 10 ^ { 11 } { L _ { \odot } } .