@article{37d4ba4d469d4a4e9dcabfacbe2e6479,
title = "Spectroscopic Confirmation of Five Galaxy Clusters at z > 1.25 in the 2500 deg2 SPT-SZ Survey",
abstract = "We present spectroscopic confirmation of five galaxy clusters at 1.25 < z < 1.5, discovered in the 2500 deg2 South Pole Telescope Sunyaev-Zel'dovich (SZ) survey. These clusters, taken from a mass-limited sample with a nearly redshift-independent selection function, have multiwavelength follow-up imaging data from the X-ray to near-IR and currently form the most homogeneous massive high-redshift cluster sample known. We identify 44 member galaxies, along with 25 field galaxies, among the five clusters, and describe the full set of observations and data products from Magellan/LDSS3 multiobject spectroscopy of these cluster fields. We briefly describe the analysis pipeline and present ensemble analyses of cluster member galaxies that demonstrate the reliability of the measured redshifts. We report z = 1.259, 1.288, 1.316, 1.401, and 1.474 for the five clusters from a combination of absorption-line (Ca ii H&K doublet - λλ3968, 3934) and emission-line ([O ii] λλ3727, 3729) spectral features. Moreover, the calculated velocity dispersions yield dynamical cluster masses in good agreement with the SZ masses for these clusters. We discuss the velocity and spatial distributions of passive and [O ii]-emitting galaxies in these clusters, showing that they are consistent with velocity segregation and biases observed in lower redshift South Pole Telescope clusters. We identify modest [O ii] emission and pronounced CN and Hδ absorption in a stacked spectrum of 28 passive galaxies with Ca ii H&K-derived redshifts. This work increases the number of spectroscopically confirmed SZ-selected galaxy clusters at z > 1.25 from three to eight, further demonstrating the efficacy of SZ selection for the highest redshift massive clusters and enabling detailed study of these systems.",
author = "G. Khullar and Bleem, {L. E.} and Bayliss, {M. B.} and Gladders, {M. D.} and Benson, {B. A.} and M. McDonald and Allen, {S. W.} and Applegate, {D. E.} and Ashby, {M. L.N.} and S. Bocquet and M. Brodwin and E. Bulbul and Canning, {R. E.A.} and R. Capasso and I. Chiu and Crawford, {T. M.} and {De Haan}, T. and Dietrich, {J. P.} and Gonzalez, {A. H.} and J. Hlavacek-Larrondo and H. Hoekstra and Holzapfel, {W. L.} and {Von Der Linden}, A. and Mantz, {A. B.} and S. Patil and Reichardt, {C. L.} and A. Saro and K. Sharon and B. Stalder and Stanford, {S. A.} and Stark, {A. A.} and V. Strazzullo",
note = "Funding Information: This work is supported by the Department of Astronomy and Astrophysics at the University of Chicago, NSF Physics Frontier Center grant PHY-1125897 to the Kavli Institute of Cosmological Physics at the University of Chicago, as well as by the Kavli Foundation, and the Gordon and Betty Moore Foundation grant GBMF 947. The South Pole Telescope is supported by the National Science Foundation through grant PLR-1248097. Funding Information: B.B. is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. Argonne National Laboratory work was supported under U.S. Department of Energy contract DE-AC02-06CH11357. M.B. was supported by National Science Foundation through grant AST-1009012. A.S. is supported by the ERC-StG “ClustersXCosmo,” grant agreement 71676. The data analyzed in this paper was taken on the 6.5 m Magellan Telescopes at the Las Campanas Observatory, Chile, supported by the Carnegie Observatories. This work is partly based on observations made with the NASA/ ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555, associated with SPT follow-up GO program 14252. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. C.R. acknowledges support from the Australian Research Council{\textquoteright}s Discovery Projects scheme (DP150103208). Publisher Copyright: {\textcopyright} 2018. The American Astronomical Society. All rights reserved..",
year = "2019",
month = jan,
day = "1",
doi = "10.3847/1538-4357/aaeed0",
language = "English",
volume = "870",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",
}