COSMOLOGICAL CONSTRAINTS FROM SUNYAEV-ZEL'DOVICH-SELECTED CLUSTERS WITH X-RAY OBSERVATIONS IN THE FIRST 178 deg[superscript 2] OF THE SOUTH POLE TELESCOPE SURVEY
Author(s)
Andersson, Karl; Bautz, Marshall W.; McDonald, Michael A.
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We use measurements from the South Pole Telescope (SPT) Sunyaev-Zel'dovich (SZ) cluster survey in combination with X-ray measurements to constrain cosmological parameters. We present a statistical method that fits for the scaling relations of the SZ and X-ray cluster observables with mass while jointly fitting for cosmology. The method is generalizable to multiple cluster observables, and self-consistently accounts for the effects of the cluster selection and uncertainties in cluster mass calibration on the derived cosmological constraints. We apply this method to a data set consisting of an SZ-selected catalog of 18 galaxy clusters at z > 0.3 from the first 178 deg[superscript 2] of the 2500 deg[superscript 2] SPT-SZ survey, with 14 clusters having X-ray observations from either Chandra or XMM-Newton. Assuming a spatially flat ΛCDM cosmological model, we find the SPT cluster sample constrains σ[subscript 8](Ω [subscript m] /0.25)[superscript 0.30] = 0.785 ± 0.037. In combination with measurements of the cosmic microwave background (CMB) power spectrum from the SPT and the seven-year Wilkinson Microwave Anisotropy Probe data, the SPT cluster sample constrains σ[subscript 8] = 0.795 ± 0.016 and Ω [subscript m] = 0.255 ± 0.016, a factor of 1.5 improvement on each parameter over the CMB data alone. We consider several extensions beyond the ΛCDM model by including the following as free parameters: the dark energy equation of state (w), the sum of the neutrino masses (Σm [subscript ν]), the effective number of relativistic species (N [subscript eff]), and a primordial non-Gaussianity (f [subscript NL]). We find that adding the SPT cluster data significantly improves the constraints on w and Σm [subscript ν] beyond those found when using measurements of the CMB, supernovae, baryon acoustic oscillations, and the Hubble constant. Considering each extension independently, we best constrain w = –0.973 ± 0.063 and the sum of neutrino masses Σm [subscript ν] < 0.28 eV at 95% confidence, a factor of 1.25 and 1.4 improvement, respectively, over the constraints without clusters. Assuming a ΛCDM model with a free N [subscript eff] and Σm [subscript ν], we measure N [subscript eff] = 3.91 ± 0.42 and constrain Σm [subscript ν] < 0.63 eV at 95% confidence. We also use the SPT cluster sample to constrain f [subscript NL] = –220 ± 317, consistent with zero primordial non-Gaussianity. Finally, we discuss the current systematic limitations due to the cluster mass calibration, and future improvements for the recently completed 2500 deg[superscript 2] SPT-SZ survey. The survey has detected ~500 clusters with a median redshift of ~0.5 and a median mass of ~2.3 × 10[superscript 14] M [subscript ☉] h[superscript –1] and, when combined with an improved cluster mass calibration and existing external cosmological data sets will significantly improve constraints on w.
Date issued
2013-01Department
MIT Kavli Institute for Astrophysics and Space ResearchJournal
The Astrophysical Journal
Publisher
IOP Publishing
Citation
Benson, B. A., T. de Haan, J. P. Dudley, C. L. Reichardt, K. A. Aird, K. Andersson, R. Armstrong, et al. “COSMOLOGICAL CONSTRAINTS FROM SUNYAEV-ZEL’DOVICH-SELECTED CLUSTERS WITH X-RAY OBSERVATIONS IN THE FIRST 178 Deg[superscript 2] OF THE SOUTH POLE TELESCOPE SURVEY.” The Astrophysical Journal 763, no. 2 (January 17, 2013): 147. © 2013 The American Astronomical Society
Version: Final published version
ISSN
0004-637X
1538-4357