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Title: SPT-CL J2040–4451: An SZ-selected galaxy cluster at z = 1.478 with significant ongoing star formation

SPT-CL J2040–4451—spectroscopically confirmed at z = 1.478—is the highest-redshift galaxy cluster yet discovered via the Sunyaev-Zel'dovich effect. SPT-CL J2040–4451 was a candidate galaxy cluster identified in the first 720 deg{sup 2} of the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey, and has been confirmed in follow-up imaging and spectroscopy. From multi-object spectroscopy with Magellan-I/Baade+IMACS we measure spectroscopic redshifts for 15 cluster member galaxies, all of which have strong [O II] λλ3727 emission. SPT-CL J2040–4451 has an SZ-measured mass of M {sub 500,} {sub SZ} = 3.2 ± 0.8 × 10{sup 14} M {sub ☉} h {sub 70}{sup −1}, corresponding to M {sub 200,} {sub SZ} = 5.8 ± 1.4 × 10{sup 14} M {sub ☉} h {sub 70}{sup −1}. The velocity dispersion measured entirely from blue star-forming members is σ {sub v} = 1500 ± 520 km s{sup –1}. The prevalence of star-forming cluster members (galaxies with >1.5 M {sub ☉} yr{sup –1}) implies that this massive, high-redshift cluster is experiencing a phase of active star formation, and supports recent results showing a marked increase in star formation occurring in galaxy clusters at z ≳ 1.4. We also compute the probability of finding a cluster as rare as this in themore » SPT-SZ survey to be >99%, indicating that its discovery is not in tension with the concordance ΛCDM cosmological model.« less
Authors:
;  [1] ; ; ;  [2] ;  [3] ;  [4] ;  [5] ; ; ; ; ; ;  [6] ; ;  [7] ;  [8] ;  [9] ; ;  [10] more »; « less
  1. Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138 (United States)
  2. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  3. Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States)
  4. University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)
  5. Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)
  6. Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)
  7. Department of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, D-81679 München (Germany)
  8. NIST Quantum Devices Group, 325 Broadway Mailcode 817.03, Boulder, CO 80305 (United States)
  9. Departamento de Astronomia y Astrosifica, Pontificia Universidad Catolica (Chile)
  10. Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada)
Publication Date:
OSTI Identifier:
22370517
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 794; 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; COSMOLOGICAL MODELS; DISPERSIONS; EMISSION; EVOLUTION; GALAXIES; GALAXY CLUSTERS; MASS; PROBABILITY; RED SHIFT; SPECTROSCOPY; STARS; TELESCOPES; UNIVERSE; VELOCITY