Temperature bias in measurements of the Hubble constant using the Sunyaev - Zeldovich effect
Mar, 2003
e-Print:
- astro-ph/0303355 [astro-ph]
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Abstract: (arXiv)
Measurements of the Hubble constant to distant galaxy clusters using the Sunyaev-Zeldovich effect are systematically low in comparison to values obtained by other means. These measurements usually assume a spherical isothermal model for the intracluster medium (ICM). We present the results of a statistical analysis of {\em temperature bias} in determinations in a sample of 27 numerically simulated X-ray clusters drawn from a CDM model at z=0.5. We employ adaptive mesh refinement to provide high resolution (15.6 h) in cluster cores which dominate the X-ray and radio signals. Fitting synthetic X-ray and y-parameter maps to the standard isothermal beta model, we find a broad, skewed distribution in with a mean, median, and standard deviation of 0.89, 0.83 and 0.32 respectively, where is the value of derived by using Sunyaev-Zeldovich effect method and is the value used in the cosmological simulation. We find that the clusters' declining temperature profiles systematically lower estimates of by 10% to 20%. The declining temperature profile of our adiabatic system is consistent with the result including radiative cooling and supernovae feedback (Loken et al. 2002). We thereby introduce a non-isothermal model as an improvement. Applying the non-isothermal model to the refined sample with well-fitted temperature profile, the value of f improves 9% relative to the actual value. The study of the morphology and the clumping effects conclude that these two factors combine to induce scatter in f of 30 %.References(0)
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