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arXiv 1012.1106astro-ph.COastro-ph.IM
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用Sunyaev-Zel'dovich效应测量冷核星系团的总质量

Biased total mass of cool core galaxy clusters by Sunyaev-Zel'dovich effect measurements

A. Conte, M. De Petris, B. Comis, L. Lamagna, S. De Gregori

摘要:

来自星系团的Sunyaev Zel'dovich(SZ)效应是研究大尺度宇宙的最有力的宇宙学工具之一。SZ效应的最大优点是它的红移独立性,这在可见光和X射线观测中不是这样。它使我们能够直接估计集群的总质量从综合康普顿化参数Y,即使是遥远的集群。然而,不完全了解簇内介质(ICM)物理可能会影响结果。通过考虑ICM的自相似温度和密度分布,我们研究了不同的ICM形态如何影响集群总质量的估计。在迄今为止观察到的高百分比冷核(CC)星团的帮助下,本分析侧重于研究这类天体。考虑了Chandra观测到的8个邻近(0.1 < z < 0.5)和高质量(M > 10^(14)M_sun)星系团的样本。我们模拟SZ观测这些集群通过X射线派生的信息,并分析了模拟SZ数据再次与ICM的等温β模型配置文件的简单假设。使用不同的假设集合恢复集群总质量的偏差估计为50%以上的情况下,流体静力平衡。考虑了视线积分和所考虑的ICM模板对总偏倚的可能贡献。总质量回收的大偏差坚定地支持,如果仍然有必要,集群建模的基础上更复杂的通用配置文件所得出的X射线观测的本地对象和流体动力学模拟。

英文摘要:

The Sunyaev Zel'dovich (SZ) effect from galaxy clusters is one of the most powerful cosmological tools for investigating the large-scale Universe. The big advantage of the SZ effect is its redshift independence, which is not the case for visible and X-ray observations. It allows us to directly estimate the cluster's total mass from the integrated comptonization parameter Y, even for distant clusters. However, not having a full knowing intra-cluster medium (ICM) physics can affect the results. By taking self-similar temperature and density profiles of the ICM into account, we studied how different ICM morphologies can affect the cluster total mass estimation. With the help of the high percentage of cool core (CC) clusters, as observed so far, the present analysis focuses on studying this class of objects. A sample of eight nearby (0.1 < z < 0.5) and high-mass (M > 10^(14) M_sun) clusters observed by Chandra was considered. We simulated SZ observations of these clusters through X-ray derived information and analyzed the mock SZ data again with the simplistic assumption of an isothermal beta-model profile for the ICM. The bias on the recovered cluster total mass using different sets of assumptions is estimated to be 50% higher in the case of hydrostatic equilibrium. Possible contributions to the total bias due to the line-of-sight integration and the considered ICM template are taken into account. The large biases on total mass recovery firmly support, if still necessary, cluster modeling based on more sophisticated universal profiles as derived by X-ray observations of local objects and hydrodynamical simulations.

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