Constraints in cosmological parameter space from the Sunyaev-Zeldovich effect and thermal bremsstrahlung

S. M. Molnar*, M. Birkinshaw, R. F. Mushotzky

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

23 Citations (Scopus)


We discuss how the space of possible cosmological parameters is constrained by the angular diameter distance function DA(z) as measured using the SZ/X-ray method, which combines the Sunyaev-Zeldovich (SZ) effect and X-ray brightness data for clusters of galaxies. New X-ray satellites and ground-based interferometers dedicated to SZ observations should soon lead to DA(z) measurements limited by systematic rather than random error. We analyze the systematic and random error budgets to make a realistic estimate of the accuracy achievable in the determination of (Ω m, ΩΛ, h), the density parameters of matter and cosmological constant, and the dimensionless Hubble constant, using D A(z) derived from the SZ/X-ray method and the position of the first "Doppler" peak in the cosmic microwave background fluctuations. We briefly study the effect of systematic errors. We find that Ω m, ΩΛ, and w are affected, but h is not, by systematic errors that grow with redshift. With as few as 70 clusters, each providing a measurement of DA(z) with a 7% random and 5% systematic error, Ωm can be constrained to ±0.2, Ω Λ to ±0.2, and h to ±0.11 (all at 3 σ). We also estimate constraints for the alternative three-parameter set (Ωm, w, h), where w is the equation-of-state parameter. The measurement of DA(z) provides constraints complementary to those from the number density of clusters in redshift space. A sample of 70 clusters (DA measured with the same accuracy as before) combined with cluster evolution results (or a known matter density) can constrain w within ±0.45 (at 3 σ). Studies of X-ray and SZ properties of clusters of galaxies promise an independent and powerful test for cosmological parameters.

Original languageEnglish
Pages (from-to)1-16
Number of pages16
JournalAstrophysical Journal
Issue number1 I
Publication statusPublished - 1 May 2002


  • Cosmological parameters
  • Cosmology: theory
  • Galaxies: clusters: general
  • X-rays: galaxies: clusters


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