MASS CALIBRATION AND COSMOLOGICAL ANALYSIS OF THE SPT-SZ GALAXY CLUSTER SAMPLE USING VELOCITY DISPERSION σ[subscript v] AND X-RAY Y[subscript X] MEASUREMENTS
Author(s)Bautz, Marshall W.; McDonald, Michael A.
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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[superscript 2] of the survey along with 63 velocity dispersion (σ [subscript v]) and 16 X-ray Y [subscript 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 [subscript v] and Y [subscript X] are consistent at the 0.6σ level, with the σ [subscript v] calibration preferring ~16% higher masses. We use the full SPT[subscript CL] data set (SZ clusters+σ [subscript v] +Y [subscript X]) to measure σ[subscript 8](Ω[subscript m]/0.27)[superscript 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 [subscript 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 [subscript ν] further reconciles the results. When we combine the SPT[subscript 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 [subscript X] calibration and 0.8σ higher than the σ [subscript 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[subscript m] = 0.299 ± 0.009 and σ[subscript 8] = 0.829 ± 0.011. Within a νCDM model we find ∑m [subscript 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).
DepartmentKavli Institute for Astrophysics and Space Research
The Astrophysical Journal
Bocquet, S., A. Saro, J. J. Mohr, K. A. Aird, M. L. N. Ashby, M. Bautz, M. Bayliss, et al. “MASS CALIBRATION AND COSMOLOGICAL ANALYSIS OF THE SPT-SZ GALAXY CLUSTER SAMPLE USING VELOCITY DISPERSION σ [subscript v] AND X-RAY Y [subscript X] MEASUREMENTS.” The Astrophysical Journal 799, no. 2 (January 30, 2015): 214. © 2015 The American Astronomical Society
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