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arXiv 0811.2199astro-ph
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结合Sunyaev-Zeldovich和X射线图像重建模拟星系团的质量分布

Reconstructing mass profiles of simulated galaxy clusters by combining Sunyaev-Zeldovich and X-ray images

S. Ameglio, S. Borgani, E. Pierpaoli, K. Dolag, S. Ettori, A. Morandi

备注：
13 pages, 11 figures, submitted to MNRAS
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摘要：

我们提出了一种方法来恢复星系团的质量配置文件相结合的热Sunyaev-Zeldovich（tSZ）和X射线成像的数据，从而避免使用任何信息的X射线光谱。该方法代表了Ameglio等人（2007）提出的几何解投影技术的发展，实现了流体静力平衡方程的求解。为了量化我们的质量重建的效率，我们将我们的技术应用到一组星系团的流体动力学模拟。我们提出了两个版本的质量重建方法。方法1是完全独立于模型的，而方法2则假设Navarro等人（1997）（NFW）提出的分析质量分布。我们发现，在恢复的质量分布的主要来源的偏见是由于流体静力平衡，这导致低估的质量约10%，在r_500和高达20%的维里半径的偏差。方法1提供了一个重建的质量，它是偏低约10%，与20%的散射，相对于真实的质量分布。方法2被证明是更稳定的，减少了分散到10%，但有一个更大的偏差20%，主要是由郊区的平衡偏差引起的。为了更好地理解方法2的结果，我们检查它在多大程度上可以恢复质量和浓度参数之间的关系。当分析3D质量分布时，我们发现，包括在拟合维里半径的内5%偏置高的晕浓度。此外，在固定质量下，较热的星团往往具有较大的浓度。我们的程序恢复的浓度参数基本上是无偏的，但分散约50%。

英文摘要：

We present a method to recover mass profiles of galaxy clusters by combining data on thermal Sunyaev-Zeldovich (tSZ) and X-ray imaging, thereby avoiding to use any information on X-ray spectroscopy. This method, which represents a development of the geometrical deprojection technique presented in Ameglio et al. (2007), implements the solution of the hydrostatic equilibrium equation. In order to quantify the efficiency of our mass reconstructions, we apply our technique to a set of hydrodynamical simulations of galaxy clusters. We propose two versions of our method of mass reconstruction. Method 1 is completely model-independent, while Method 2 assumes instead the analytic mass profile proposed by Navarro et al. (1997) (NFW). We find that the main source of bias in recovering the mass profiles is due to deviations from hydrostatic equilibrium, which cause an underestimate of the mass of about 10 per cent at r_500 and up to 20 per cent at the virial radius. Method 1 provides a reconstructed mass which is biased low by about 10 per cent, with a 20 per cent scatter, with respect to the true mass profiles. Method 2 proves to be more stable, reducing the scatter to 10 per cent, but with a larger bias of 20 per cent, mainly induced by the deviations from equilibrium in the outskirts. To better understand the results of Method 2, we check how well it allows to recover the relation between mass and concentration parameter. When analyzing the 3D mass profiles we find that including in the fit the inner 5 per cent of the virial radius biases high the halo concentration. Also, at a fixed mass, hotter clusters tend to have larger concentration. Our procedure recovers the concentration parameter essentially unbiased but with a scatter of about 50 per cent.

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