arXiv 0804.19092008-04-11astro-ph

用XMM-牛顿观测大样本星系团的径向温度分布

Radial temperature profiles for a large sample of galaxy clusters observed with XMM-Newton

A. Leccardi, S. Molendi

备注：: 18 pages, 26 figures, accepted for publication in A&A
DOI：: 10.1051/0004-6361:200809538

摘要：

目标。我们测量，尽可能远，径向温度分布的样本~50热，中间红移星系团，从XMM-牛顿档案选择，保持系统误差控制。方法.我们的工作有两个重大改进。首先，我们使用背景建模，而不是背景减法，Cash统计量，而不是卡方;这种方法需要仔细表征所有背景成分。其次，我们详细评估了系统效应。我们进行了两组测试：在分析之前，我们利用广泛的模拟来量化不同光谱分量对模拟光谱的影响;在分析之后，我们研究了当选择不同的关键参数时，测量的温度分布如何变化。结果平均温度分布下降超过0.2 R_{180}，我们第一次提供了一个评估的来源和系统的不确定性的大小。当比较我们的配置文件从流体动力学模拟得到的，我们发现超过~0.2 R_{180}的斜率是相似的。我们的平均配置文件是类似的，但有点平坦，相对于以前的观测工作，可能是由于不同程度的表征系统的影响。结论.这项工作使我们不仅可以约束与信心集群温度分布在外部区域，而且，从更一般的角度来看，探索目前的X射线实验（特别是XMM-牛顿）的限制相对于低表面亮度发射的分析。

英文摘要：

Aims. We measure, as far out as possible, radial temperature profiles for a sample of ~50 hot, intermediate redshift galaxy clusters, selected from the XMM-Newton archive, keeping systematic errors under control. Methods. Our work is characterized by two major improvements. Firstly, we use the background modeling, rather than the background subtraction, and the Cash statistic rather than the chi square; this method requires a careful characterization of all background components. Secondly, we assess in details systematic effects. We perform two groups of test: prior to the analysis, we make use of extensive simulations to quantify the impact of different spectral components on simulated spectra; after the analysis, we investigate how the measured temperature profile changes, when choosing different key parameters. Results. The mean temperature profile declines beyond 0.2 R_{180}; for the first time we provide an assessment of the source and the magnitude of systematic uncertainties. When comparing our profile with that obtained from hydrodynamic simulations, we find the slopes beyond ~0.2 R_{180} to be similar. Our mean profile is similar but somewhat flatter with respect to that obtained by previous observational works, possibly as a consequence of a different level of characterization of systematic effects. Conclusions. This work allows us not only to constrain with confidence cluster temperature profiles in outer regions, but also, from a more general point of view, to explore the limits of the current X-ray experiments (in particular XMM-Newton) with respect to the analysis of low surface brightness emission.

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