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Published January 1, 2014 | Version v1
Journal article Open

Planck 2013 results. XX. Cosmology from Sunyaev-Zeldovich cluster counts

Creators

  • 1. Cardiff Univ, Sch Phys & Astron, Cardiff CF24 3AA, S Glam, Wales
  • 2. Univ Paris 11, CNRS, Inst Astrophys Spatiale, UMR 8617, Batiment 121, F-91405 Orsay, France
  • 3. Univ Oxford, Sub Dept Astrophys, Oxford OX1 3RH, England
  • 4. CEA Saclay, Univ Paris Diderot, CEA DSM CNRS, IRFU Serv Astrophys,Lab AIM, F-91191 Gif Sur Yvette, France
  • 5. Univ Salamanca, Fac Ciencias, Dept Fis Fundamental, E-37008 Salamanca, Spain
  • 6. SISSA, Astrophys Sect, I-34136 Trieste, Italy
  • 7. Univ Cantabria, CSIC, Inst Fis Cantabria, E-39005 Santander, Spain
  • 8. Inst Astrofis Canarias, Tenerife 38200, Spain
  • 9. Univ Granada, Fac Ciencias, Dept Fis Teor & Cosmos, E-18071 Granada, Spain
  • 10. Univ Manchester, Sch Phys & Astron, Jodrell Bank Ctr Astrophys, Manchester M13 9PL, Lancs, England
  • 11. Univ Grenoble 1, CNRS, Inst Neel, F-38042 Grenoble, France
  • 12. CNRS, IRAP, F-31028 Toulouse 4, France

Description

We present constraints on cosmological parameters using number counts as a function of redshift for a sub-sample of 189 galaxy clusters from the Planck SZ (PSZ) catalogue. The PSZ is selected through the signature of the Sunyaev-Zeldovich (SZ) effect, and the sub-sample used here has a signal-to-noise threshold of seven, with each object confirmed as a cluster and all but one with a redshift estimate. We discuss the completeness of the sample and our construction of a likelihood analysis. Using a relation between mass M and SZ signal Y calibrated to X-ray measurements, we derive constraints on the power spectrum amplitude sigma(8) and matter density parameter Omega(m) in a flat Lambda CDM model. We test the robustness of our estimates and find that possible biases in the Y-M relation and the halo mass function are larger than the statistical uncertainties from the cluster sample. Assuming the X-ray determined mass to be biased low relative to the true mass by between zero and 30%, motivated by comparison of the observed mass scaling relations to those from a set of numerical simulations, we find that sigma(8) = 0.75 +/- 0.03, Omega(m) = 0.29 +/- 0.02, and sigma(8)(Omega(m)/0.27)(0.3) = 0.764 +/- 0.025. The value of sigma(8) is degenerate with the mass bias; if the latter is fixed to a value of 20% (the central value from numerical simulations) we find sigma(8)(Omega(m)/0.27)(0.3) = 0.78 +/- 0.01 and a tighter one-dimensional range sigma(8) = 0.77 +/- 0.02. We find that the larger values of sigma(8) and Omega(m) preferred by Planck's measurements of the primary CMB anisotropies can be accommodated by a mass bias of about 40%. Alternatively, consistency with the primary CMB constraints can be achieved by inclusion of processes that suppress power on small scales relative to the Lambda CDM model, such as a component of massive neutrinos. We place our results in the context of other determinations of cosmological parameters, and discuss issues that need to be resolved in order to make further progress in this field.

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