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

• Published in: The Astrophysical Journal
• Main Authors: Bocquet, S., Crites, A. T., Lueker, M., Padin, S., Shirokoff, E., Staniszewski, Z., Williamson, R.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Astronomical Society 2015
• Subjects: cosmic background radiation; cosmology: observations; galaxies: clusters: individual; large-scale structure of universe; South Pole; South pole
• Online Access: https://doi.org/10.1088/0004-637X/799/2/214

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 ...