Smail, IanGeach, J. E.Swinbank, A. M.Tadaki, K.Arumugam, V.Hartley, W.Almaini, O.Bremer, M. N.Chapin, E.Chapman, S. C.Danielson, A. L. R.Edge, A. C.Scott, D.Simpson, C. J.Simpson, J. M.Conselice, C.Dunlop, J. S.Ivison, R. J.Karim, A.Kodama, T.Mortlock, A.Robson, E. I.Roseboom, I.Thomson, A. P.van der Werf, P. P.Webb, T. M. A.2014-03-122014-03-122013-12-11Smail, Ian, J. E. Geach, A. M. Swinbank, K. Tadaki, et al. 2013. "The SCUBA-2 Cosmology Legacy Survey: Ultraluminous star-forming galaxies in a z=1.6 cluster." The Astrophysical Journal 182(1): 19.0004-637Xhttp://hdl.handle.net/10222/45436http://dx.doi.org/10.1088/0004-637X/782/1/19We analyse new SCUBA-2 submillimeter and archival SPIRE far-infrared imaging of a z=1.62 cluster, Cl0218.3-0510, which lies in the UKIDSS/UDS field of the SCUBA-2 Cosmology Legacy Survey. Combining these tracers of obscured star formation activity with the extensive photometric and spectroscopic information available for this field, we identify 31 far-infrared/submillimeter-detected probable cluster members with bolometric luminosities >1e12 Lo and show that by virtue of their dust content and activity, these represent some of the reddest and brightest galaxies in this structure. We exploit Cycle-1 ALMA submillimeter continuum imaging which covers one of these sources to confirm the identification of a SCUBA-2-detected ultraluminous star-forming galaxy in this structure. Integrating the total star-formation activity in the central region of the structure, we estimate that it is an order of magnitude higher (in a mass-normalised sense) than clusters at z~0.5-1. However, we also find that the most active cluster members do not reside in the densest regions of the structure, which instead host a population of passive and massive, red galaxies. We suggest that while the passive and active populations have comparable near-infrared luminosities at z=1.6, M(H)~-23, the subsequent stronger fading of the more active galaxies means that they will evolve into passive systems at the present-day which are less luminous than the descendants of those galaxies which were already passive at z~1.6 (M(H)~-20.5 and M(H)~-21.5 respectively at z~0). We conclude that the massive galaxy population in the dense cores of present-day clusters were already in place at z=1.6 and that in Cl0218.3-0510 we are seeing continuing infall of less extreme, but still ultraluminous, star-forming galaxies onto a pre-existing structure.article182119