skip to main content

Title: KECK/MOSFIRE SPECTROSCOPIC CONFIRMATION OF A VIRGO-LIKE CLUSTER ANCESTOR AT z = 2.095

We present spectroscopic confirmation of a galaxy cluster at z = 2.095 in the COSMOS field. This galaxy cluster was first reported in the ZFOURGE survey as harboring evolved massive galaxies using photometric redshifts derived with deep near-infrared (NIR) medium-band filters. We obtain medium-resolution (R ∼ 3600) NIR spectroscopy with MOSFIRE on the Keck 1 telescope and secure 180 redshifts in a 12' × 12' region. We find a prominent spike of 57 galaxies at z = 2.095 corresponding to the galaxy cluster. The cluster velocity dispersion is measured to be σ{sub v1D}  =  552 ± 52 km s{sup –1}. This is the first study of a galaxy cluster in this redshift range (z ≳ 2.0) with the combination of spectral resolution (∼26 km s{sup –1}) and the number of confirmed members (>50) needed to impose a meaningful constraint on the cluster velocity dispersion and map its members over a large field of view. Our ΛCDM cosmological simulation suggests that this cluster will most likely evolve into a Virgo-like cluster with M {sub vir} = 10{sup 14.4} {sup ±} {sup 0.3} M {sub ☉} (68% confidence) at z ∼ 0. The theoretical probability of finding such a cluster is ∼4%. Our results demonstrate the feasibility ofmore » studying galaxy clusters at z > 2 in the same detailed manner using multi-object NIR spectrographs as has been done in the optical in lower-redshift clusters.« less
Authors:
;  [1] ; ; ;  [2] ; ;  [3] ;  [4] ;  [5] ; ;  [6]
  1. Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia)
  2. Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122 (Australia)
  3. George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States)
  4. Department of Physics and Astronomy, Macquarie University, Sydney, NSW 2109 (Australia)
  5. School of Physics, University of Melbourne, Parksville, VIC 3010 (Australia)
  6. Sterrewacht Leiden, Leiden University, NL-2300 RA Leiden (Netherlands)
Publication Date:
OSTI Identifier:
22364569
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 795; 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 CONSTANT; COSMOLOGICAL MODELS; GALAXIES; GALAXY CLUSTERS; LIMITING VALUES; NEAR INFRARED RADIATION; NONLUMINOUS MATTER; PHOTOMETRY; RED SHIFT; RESOLUTION; TELESCOPES; UNIVERSE; VELOCITY