标题： 星系团的气体质量分数的X射线和Sunyaev-Zel'dovich效应测量 显示英文标题

标题： X-ray and Sunyaev-Zel'dovich Effect Measurements of the Gas Mass Fraction in Galaxy Clusters

摘要： 我们利用钱德拉X射线数据和OVRO/BIMA干涉仪测量的太阳热效应，得出了38个质量较大的星系团（红移范围从0.14到0.89）的气体质量分数。我们使用了三种气体分布模型：(1) 对超过100千秒差距半径的X射线数据以及所有SZE数据进行联合拟合的等温β模型；(2) 对所有X射线和SZE数据进行联合拟合的非等温双β模型；(3) 仅对SZE空间数据进行拟合的等温β模型。我们表明，简单的等温模型很好地描述了具有广泛形态特性的星系团核心外的星系际介质（ICM）。对于100千秒差距切割的等温β模型，X射线和SZE确定的平均气体质量分数分别为fgas(X射线)=0.110 +0.003-0.003 +0.006-0.018和fgas(SZE)=0.116 +0.005-0.005 +0.009-0.026，其中不确定性先统计后系统，在68%置信水平下。对于非等温双β模型，fgas(X射线)=0.119 +0.003-0.003 +0.007-0.014和fgas(SZE)=0.121 +0.005-0.005 +0.009-0.016。对于仅SZE模型，fgas(SZE)=0.120 +0.009-0.009 +0.009-0.027。我们的结果表明，r2500范围内气体质量分数与宇宙重子分数之比为0.68 +0.10-0.16，该范围包括统计和系统不确定性。通过假设星团气体质量分数与红移无关，我们发现结果与标准ΛCDM宇宙学一致，并且与物质主导的平坦宇宙不一致。 显示英文摘要

摘要： We present gas mass fractions of 38 massive galaxy clusters spanning redshifts from 0.14 to 0.89, derived from Chandra X-ray data and OVRO/BIMA interferometric Sunyaev-Zel'dovich Effect measurements. We use three models for the gas distribution: (1) an isothermal beta-model fit jointly to the X-ray data at radii beyond 100 kpc and to all of the SZE data,(2) a non-isothermal double beta-model fit jointly to all of the X-ray and SZE data, and (3) an isothermal beta-model fit only to the SZE spatial data. We show that the simple isothermal model well characterizes the intracluster medium (ICM) outside of the cluster core in clusters with a wide range of morphological properties. The X-ray and SZE determinations of mean gas mass fractions for the 100 kpc-cut isothermal beta-model are fgas(X-ray)=0.110 +0.003-0.003 +0.006-0.018 and fgas(SZE)=0.116 +0.005-0.005 +0.009-0.026, where uncertainties are statistical followed by systematic at 68% confidence. For the non-isothermal double beta-model, fgas(X-ray)=0.119 +0.003-0.003 +0.007-0.014 and fgas(SZE)=0.121 +0.005-0.005 +0.009-0.016. For the SZE-only model, fgas(SZE)=0.120 +0.009-0.009 +0.009-0.027. Our results indicate that the ratio of the gas mass fraction within r2500 to the cosmic baryon fraction is 0.68 +0.10-0.16 where the range includes statistical and systematic uncertainties. By assuming that cluster gas mass fractions are independent of redshift, we find that the results are in agreement with standard LambdaCDM cosmology and are inconsistent with a flat matter dominated universe.