skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Spectroscopic Confirmation of Five Galaxy Clusters at z > 1.25 in the 2500 deg 2 SPT-SZ Survey

Abstract

We present spectroscopic confirmation of five galaxy clusters at 1.25 < z < 1.5, discovered in the 2500 deg 2 South Pole Telescope Sunyaev-Zel’dovich (SPT-SZ) survey. These clusters, taken from a mass-limited sample with a nearly redshift independent selection function, have multi-wavelength 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 multi-object 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 - λλ3968,3934Å) and emission-line ([OII] λλ3727,3729Å) spectral features. Moreover, the calculated velocity dispersions yield dynamical cluster masses in good agreement with SZ masses for these clusters. We discuss the velocity and spatial distributions of passive and [OII]-emitting galaxies in these clusters, showing that they are consistent with velocity segregation and biases observed in lower redshift SPT clusters. We identify modest [OII] emission and pronounced CNmore » 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.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science - Office of High Energy Physics; University of Chicago - Department of Astronomy and Astrophysics; National Science Foundation (NSF); Gordon and Betty Moore Foundation
OSTI Identifier:
1494711
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 870; Journal Issue: 1; Journal ID: ISSN 0004-637X
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
galaxies: clusters: general; galaxies: distances and redshifts; galaxies: evolution; galaxies: kinematics and dynamics; galaxies: observations

Citation Formats

Khullar, G., Bleem, L. E., Bayliss, M. B., Gladders, M. D., Benson, B. A., McDonald, M., Allen, S. W., Applegate, D. E., Ashby, M. L. N., and Bocquet, S. Spectroscopic Confirmation of Five Galaxy Clusters at z > 1.25 in the 2500 deg2 SPT-SZ Survey. United States: N. p., 2019. Web. doi:10.3847/1538-4357/aaeed0.
Khullar, G., Bleem, L. E., Bayliss, M. B., Gladders, M. D., Benson, B. A., McDonald, M., Allen, S. W., Applegate, D. E., Ashby, M. L. N., & Bocquet, S. Spectroscopic Confirmation of Five Galaxy Clusters at z > 1.25 in the 2500 deg2 SPT-SZ Survey. United States. doi:10.3847/1538-4357/aaeed0.
Khullar, G., Bleem, L. E., Bayliss, M. B., Gladders, M. D., Benson, B. A., McDonald, M., Allen, S. W., Applegate, D. E., Ashby, M. L. N., and Bocquet, S. Tue . "Spectroscopic Confirmation of Five Galaxy Clusters at z > 1.25 in the 2500 deg2 SPT-SZ Survey". United States. doi:10.3847/1538-4357/aaeed0.
@article{osti_1494711,
title = {Spectroscopic Confirmation of Five Galaxy Clusters at z > 1.25 in the 2500 deg2 SPT-SZ Survey},
author = {Khullar, G. and Bleem, L. E. and Bayliss, M. B. and Gladders, M. D. and Benson, B. A. and McDonald, M. and Allen, S. W. and Applegate, D. E. and Ashby, M. L. N. and Bocquet, S.},
abstractNote = {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 (SPT-SZ) survey. These clusters, taken from a mass-limited sample with a nearly redshift independent selection function, have multi-wavelength 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 multi-object 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 - λλ3968,3934Å) and emission-line ([OII] λλ3727,3729Å) spectral features. Moreover, the calculated velocity dispersions yield dynamical cluster masses in good agreement with SZ masses for these clusters. We discuss the velocity and spatial distributions of passive and [OII]-emitting galaxies in these clusters, showing that they are consistent with velocity segregation and biases observed in lower redshift SPT clusters. We identify modest [OII] 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.},
doi = {10.3847/1538-4357/aaeed0},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 870,
place = {United States},
year = {2019},
month = {1}
}