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arXiv 0705.3288astro-ph
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利用Sunyaev-Zel'dovich效应测量哈勃常数的系统误差

Systematic Errors in the Hubble Constant Measurement from the Sunyaev-Zel'dovich effect

Hajime Kawahara, Tetsu Kitayama, Shin Sasaki, Yasushi Suto

摘要:

根据Sunyaev-Zel'dovich效应和星系团X射线观测的综合分析,估算的哈勃常数比其他方法估算的值系统地低10- 15%。我们研究的起源系统低估使用分析模型的团内介质(ICM),并比较预测与理想的三轴模型和从宇宙流体动力学模拟中提取的集群。我们确定了三个重要来源的系统误差;密度和温度的不均匀性在ICM中,偏离等温线,和非球面。特别是,前两者的组合导致系统的ICM光谱温度相对于其发射加权的低估。我们发现,这三个系统很好地再现了观测到的偏差和固有的色散的哈勃常数估计从Sunyaev-Zel'dovich效应。

英文摘要:

The Hubble constant estimated from the combined analysis of the Sunyaev-Zel'dovich effect and X-ray observations of galaxy clusters is systematically lower than those from other methods by 10-15 percent. We examine the origin of the systematic underestimate using an analytic model of the intracluster medium (ICM), and compare the prediction with idealistic triaxial models and with clusters extracted from cosmological hydrodynamical simulations. We identify three important sources for the systematic errors; density and temperature inhomogeneities in the ICM, departures from isothermality, and asphericity. In particular, the combination of the first two leads to the systematic underestimate of the ICM spectroscopic temperature relative to its emission-weighed one. We find that these three systematics well reproduce both the observed bias and the intrinsic dispersions of the Hubble constant estimated from the Sunyaev-Zel'dovich effect.

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