1211.6668 (J. E. Geach et al.)

The SCUBA-2 Cosmology Legacy Survey: blank-field number counts of 450um-selected galaxies and their contribution to the cosmic infrared background    [PDF]

J. E. Geach, E. L. Chapin, K. E. K. Coppin, J. S. Dunlop, M. Halpern, Ian Smail, P. van der Werf, S. Serjeant, D. Farrah, I. Roseboom, T. Targett, V. Arumugam, V. Asboth, A. Blain, A. Chrysostomou, C. Clarke, R. J. Ivison, S. L. Jones, A. Karim, T. Mackenzie, R. Meijerink, M. J. Michalowski, D. Scott, J. Simpson, A. M. Swinbank, D. Alexander, O. Almaini, I. Aretxaga, P. Best, S. Chapman, D. L. Clements, C. Conselice, A. L. R. Danielson, S. Eales, A. C. Edge, A. Gibb, D. Hughes, T. Jenness, K. K. Knudsen, C. Lacey, G. Marsden, R. McMahon, S. Oliver, M. J. Page, J. A. Peacock, D. Rigopoulou, E. I. Robson, M. Spaans, J. Stevens, T. M. A. Webb, C. Willott, C. D. Wilson, M. Zemcov

The first deep blank-field 450um map (1-sigma~1.3mJy) 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 COSMOS field, in the footprint of the HST CANDELS area. Using 60 submillimetre galaxies (SMGs) detected at >3.75-sigma, we evaluate the number counts of 450um-selected galaxies with flux densities S_450>5mJy. 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 ~200um) into the individual galaxies responsible for its emission than has previously been possible at this wavelength. At S_450>5mJy we resolve (7.4[+/-]0.7)x10^-2 MJy/sr of the CIB at 450um (equivalent to 16[+/-]7% of the absolute brightness measured by COBE at this wavelength) into point sources. A further ~40% of the CIB can be recovered through a statistical stack of 24um emitters in this field, indicating that the majority (~60%) of the CIB at 450um is emitted by galaxies with S_450>2mJy. The average redshift of 450um emitters identified with an optical/near-infrared counterpart is estimated to be =1.3, implying that the galaxies in the sample are in the ultraluminous class (L_IR~1.1x10^12 L_sun). If the galaxies contributing to the statistical stack lie at similar redshifts, then the majority of the CIB at 450um is emitted by galaxies in the LIRG class with L_IR>3.6x10^11 L_sun.

View original: http://arxiv.org/abs/1211.6668