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Published February 1, 2015 | Published + Submitted
Journal Article Open

Mass Calibration and Cosmological Analysis of the SPT-SZ Galaxy Cluster Sample Using Velocity Dispersion σ_v and X-Ray Y_X Measurements

Abstract

We present a velocity-dispersion-based mass calibration of the South Pole Telescope Sunyaev-Zel'dovich effect survey (SPT-SZ) galaxy cluster sample. Using a homogeneously selected sample of 100 cluster candidates from 720 deg^2 of the survey along with 63 velocity dispersion (σ_v) and 16 X-ray Y_X measurements of sample clusters, we simultaneously calibrate the mass-observable relation and constrain cosmological parameters. Our method accounts for cluster selection, cosmological sensitivity, and uncertainties in the mass calibrators. The calibrations using σ_v and Y_X are consistent at the 0.6σ level, with the σ_v calibration preferring ~16% higher masses. We use the full SP_(TCL) data set (SZ clusters+σ_v +Y_X) to measure σ_g(Ω_m/0.27)^(0.3) = 0.809 ± 0.036 within a flat ΛCDM model. The SPT cluster abundance is lower than preferred by either the WMAP9 or Planck+WMAP9 polarization (WP) data, but assuming that the sum of the neutrino masses is ∑m_ν = 0.06 eV, we find the data sets to be consistent at the 1.0σ level for WMAP9 and 1.5σ for Planck+WP. Allowing for larger ∑m_ν further reconciles the results. When we combine the SPT_(CL) and Planck+WP data sets with information from baryon acoustic oscillations and Type Ia supernovae, the preferred cluster masses are 1.9σ higher than the Y_X calibration and 0.8σ higher than the σ_v calibration. Given the scale of these shifts (~44% and ~23% in mass, respectively), we execute a goodness-of-fit test; it reveals no tension, indicating that the best-fit model provides an adequate description of the data. Using the multi-probe data set, we measure Ω_m = 0.299 ± 0.009 and σ_g = 0.829 ± 0.011. Within a νCDM model we find ∑m_ν = 0.148 ± 0.081 eV. We present a consistency test of the cosmic growth rate using SPT clusters. Allowing both the growth index γ and the dark energy equation-of-state parameter w to vary, we find γ = 0.73 ± 0.28 and w = –1.007 ± 0.065, demonstrating that the expansion and the growth histories are consistent with a ΛCDM universe (γ = 0.55; w = –1).

Additional Information

© 2015 American Astronomical Society. Received 2014 July 11; accepted 2014 November 29; published 2015 January 30. We acknowledge the support of the DFG Cluster of Excellence "Origin and Structure of the Universe" and the Transregio program TR33 "The Dark Universe." The calculations have been carried out on the computing facilities of the Computational Center for Particle and Astrophysics (C2PAP) and of the Leibniz Supercomputer Center (LRZ). Optical spectroscopic data from VLT programs 086.A-0741 and 286.A-5021 and Gemini program GS-2009B-Q-16 were included in this work. Additional data were obtained with the 6.5 m Magellan Telescopes, which is located at the Las Campanas Observatory in Chile. 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 withNASA. The South Pole Telescope is supported by the National Science Foundation through grant PLR-1248097. Partial support is also provided by the NSF Physics Frontier Center grant PHY-1125897 to the Kavli Institute of Cosmological Physics at the University of Chicago, the Kavli Foundation and the Gordon and Betty Moore Foundation grant GBMF 947. Galaxy cluster research at Harvard is supported by NSF grant AST-1009012, and research at SAO is supported in part by NSF grants AST-1009649 and MRI-0723073. Work at Argonne National Lab is supported by UChicago Argonne, LLC, Operator of Argonne National Laboratory ("Argonne"). Argonne, a U.S. Department of Energy Office of Science Laboratory, is operated under Contract No. DE-AC02-06CH11357. The McGill group acknowledges funding from the National Sciences and Engineering Research Council of Canada, Canada Research Chairs Program, and the Canadian Institute for Advanced Research. Facilities: Gemini-South (GMOS), Magellan: Baade (IMACS), SPT, Spitzer/IRAC, VLT: Antu (FORS2).

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Published - 0004-637X_799_2_214.pdf

Submitted - 1407.2942v2.pdf

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Created:
August 22, 2023
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