2003/03/15 by Wen-Ching Lin, Lin, Wen-Ching, Michael L. Norman +3
Mathematics · Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #Relativity and Gravitational Theory #Statistical Mechanics and Entropy #Statistical and numerical algorithms #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0303355
f1.eps needs color, and other figures keep black and white
arxiv created 2003/03/15 · openalex publication_date 2003/03/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
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 β model for the intracluster medium (ICM). We present the results of a statistical analysis of \em temperature bias in H0 determinations in a sample of 27 numerically simulated X-ray clusters drawn from a ΛCDM model at z=0.5. We employ adaptive mesh refinement to provide high resolution (15.6 h-1 kpc) 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 f≡ H0(SZ)/H0(actual) with a mean, median, and standard deviation of 0.89, 0.83 and 0.32 respectively, where H0(SZ) is the value of H0 derived by using Sunyaev-Zeldovich effect method and H0(actual) is the value used in the cosmological simulation. We find that the clusters' declining temperature profiles systematically lower estimates of H0 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 β model as an improvement. Applying the non-isothermal β 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 %.