THE SCUBA-2 COSMOLOGY LEGACY SURVEY: ULTRALUMINOUS STAR-FORMING GALAXIES IN A z=1.6 CLUSTER

Ian Smail*, J. E. Geach, A. M. Swinbank, K. Tadaki, V. Arumugam, W. Hartley, O. Almaini, M. N. Bremer, E. Chapin, S. C. Chapman, A. L. R. Danielson, A. C. Edge, D. Scott, C. J. Simpson, J. M. Simpson, C. Conselice, J. S. Dunlop, R. J. Ivison, A. Karim, T. KodamaAlice Mortlock, E. I. Robson, I. Roseboom, A. P. Thomson, P. P. van der Werf, T. M. A. Webb

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

We analyze new SCUBA-2 submillimeter and archival SPIRE far-infrared imaging of a z = 1.62 cluster, Cl 0218.3-0510, which lies in the UKIRT Infrared Deep Sky Survey/Ultra-Deep Survey 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 greater than or similar to 10(12) L-circle dot 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 ALMA submillimeter continuum observations, which cover 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-normalized sense) than clusters at z similar to 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 similar to -23, the subsequent stronger fading of the more active galaxies means that they will evolve into passive systems at the present day that are less luminous than the descendants of those galaxies that were already passive at z similar to 1.6 (M-H similar to -20.5 and M-H similar to -21.5, respectively, at z similar to 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 Cl 0218.3-0510 we are seeing continuing infall of less extreme, but still ultraluminous, star-forming galaxies onto a pre-existing structure.

Original languageEnglish
Article number19
Number of pages15
JournalAstrophysical Journal
Volume782
Issue number1
DOIs
Publication statusPublished - 10 Feb 2014

Keywords / Materials (for Non-textual outputs)

  • cosmology: observations
  • galaxies: clusters: individual (Cl0218.3-0510)
  • galaxies: evolution
  • galaxies: formation
  • DEEP-FIELD-SOUTH
  • PANORAMIC H-ALPHA
  • RED-SEQUENCE
  • SUBMILLIMETER GALAXIES
  • EXTRAGALACTIC SURVEY
  • MIDINFRARED COUNTERPARTS
  • LUMINOSITY FUNCTION
  • BOLOMETER CAMERA
  • DISTANT CLUSTERS
  • BILLION YEARS

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