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Title: WFC3 GRISM CONFIRMATION OF THE DISTANT CLUSTER Cl J1449+0856 AT (z) = 2.00: QUIESCENT AND STAR-FORMING GALAXY POPULATIONS

We present deep Hubble Space Telescope Wide Field Camera 3 (HST/WFC3) slitless spectroscopic observations of the distant cluster Cl J1449+0856. These cover a single pointing with 18 orbits of G141 spectroscopy and F140W imaging, allowing us to derive secure redshifts down to M{sub 140} ∼ 25.5 AB and 3σ line fluxes of ∼5 × 10{sup –18} erg s{sup –1} cm{sup –2}. In particular, we were able to spectroscopically confirm 12 early-type galaxies (ETGs) in the field up to z ∼ 3, 6 of which are in the cluster core, which represents the first direct spectroscopic confirmation of quiescent galaxies in a z = 2 cluster environment. With 140 redshifts in a ∼6 arcmin{sup 2} field, we can trace the spatial and redshift galaxy distribution in the cluster core and background field. We find two strong peaks at z = 2.00 and z = 2.07, where only one was seen in our previously published ground-based data. Due to the spectroscopic confirmation of the cluster ETGs, we can now reevaluate the redshift of Cl J1449+0856 at z = 2.00, rather than z = 2.07, with the background overdensity being revealed to be sparse and {sup s}heet{sup -}like. This presents an interesting casemore » of chance alignment of two close yet unrelated structures, each one preferentially selected by different observing strategies. With 6 quiescent or early-type spectroscopic members and 20 star-forming ones, Cl J1449+0856 is now reliably confirmed to be at z = 2.00. The identified members can now allow for a detailed study of galaxy properties in the densest environment at z = 2.« less
Authors:
; ;  [1] ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7]
  1. Laboratoire AIM-Paris-Saclay, CEA/DSM-CNRS-Université Paris Diderot, Irfu/Service d'Astrophysique, CEA Saclay, Orme des Merisiers, F-91191 Gif sur Yvette (France)
  2. Institute for Astronomy, ETH Zürich Wolfgang-Pauli-strasse 27, 8093 Zürich (Switzerland)
  3. INAF-Osservatorio Astronomico di Padova Vicolo dell'Osservatorio 5, I-35122 Padova (Italy)
  4. University of Helsinki, P.O. Box 33 (Yliopistonkatu 4), FI-00014 Helsinki (Finland)
  5. Università di Bologna, Dipartimento di Astronomia Via Ranzani 1, I-40127 Bologna (Italy)
  6. School of Physics and Astronomy, University of Minnesota 116 Church Street Southeast, Minneapolis, MN 55455 (United States)
  7. Subaru Telescope, National Astronomical Observatory of Japan 650 North A'ohoku Place, Hilo, HI 96720 (United States)
Publication Date:
OSTI Identifier:
22270891
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 776; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; CAMERAS; GALAXIES; GALAXY CLUSTERS; ORBITS; RED SHIFT; STAR CLUSTERS; STAR EVOLUTION; STARS