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Fig. 2


Gas-mass fraction (red, open circles), stellar mass fraction (green, open stars), and baryon-mass fraction (black, open triangles) as a function of the total mass and the best fits excluding A2065 and A2029 in the same colors with solid line. The stellar mass fraction in our observational sample decreases with increasing cluster mass with (20  ±  4)% intrinsic scatter for the 19 clusters. For comparison, we also show the gas-mass fraction (gray, solid circles), stellar mass fraction in galaxies (gray, solid stars), and the sum of these two fractions (gray, solid triangles) for the simulated sample of 21 clusters with AGN feedback in Puchwein et al. (2010), as well as the gas mass fractions of the X-ray selected groups in Sun et al. (2009; gray, open boxes) and near-infrared selected groups in Dai et al. (2010; gray, open diamonds). The best fit of the baryon-mass fraction as a function of the total mass of the observational sample in Lin et al. (2003) is shown in gray with dot-dashed line. The gray band shows the 1σ measurement from the WMAP 5-year result (Dunkley et al. 2009). A2142 displays a baryon-mass fraction of 0.198  ±  0.008, which exceeds the WMAP result with a 3σ significance. The best fit of the gas-mass fractions combining our clusters and the clusters in Sun et al. (2009) is shown in red with dashed line with (26  ±  8)% intrinsic scatter.

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