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

Journal Article · Sat Nov 01 04:00:00 EDT 2014 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/795/1/L20· OSTI ID:22364569

Yuan, Tiantian; Kewley, Lisa J. ^[1]; Nanayakkara, Themiya; Kacprzak, Glenn G.; Glazebrook, Karl ^[2]; Tran, Kim-Vy H.; Tomczak, Adam R. ^[3]; Spitler, Lee R. ^[4]; Poole, Gregory B. ^[5]; Labbé, Ivo; Straatman, Caroline M. S. ^[6]

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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)

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 of 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.

• OSTI ID: 22364569
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 795; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMOLOGICAL CONSTANT
COSMOLOGICAL MODELS
GALAXIES
GALAXY CLUSTERS
LIMITING VALUES
NEAR INFRARED RADIATION
NONLUMINOUS MATTER
PHOTOMETRY
RED SHIFT
RESOLUTION
TELESCOPES
UNIVERSE
VELOCITY