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arXiv 1010.0249astro-ph.CO
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Sunyaev-Zel'dovich流质关系中团簇结构和动力学状态对散射的影响

The Impact of Cluster Structure and Dynamical State on Scatter in the Sunyaev-Zel'dovich Flux-Mass Relation

H. -Y. Karen Yang, Suman Bhattacharya, Paul M. Ricker

摘要:

来自星系团巡天的宇宙学约束依赖于从质量-可观测关系得到的精确质量估计。为了避免系统偏差和减少不确定性,我们利用星系团形成的流体动力学模拟研究了平均Sunyaev-Zel'dovich(SZ)通量-质量关系的内禀散射的形式和物理根源。我们检验了对数正态散射的假设,并检测到不可忽略的正偏度和峰度(> 0.5)的限制质量和红移范围很广。这些高阶矩应该包括在参数化的散射,以避免偏见的宇宙学约束。我们调查的散射源,将其与集群形态,晕浓度和动态状态的措施,我们量化的个人贡献,从每个来源。我们发现在统计上,动力学状态的影响是微弱的,因此,由于合并的选择偏差是可以忽略的。另一方面,散射和晕圈浓度之间存在强相关性,这可以用于显著降低散射(对于z = 0的簇,从12.07%降低到7.34%或降低~40%)。我们还表明,交叉校准相结合的信息,从X射线随访可以用来减少在通量-质量关系的散射,也确定在X射线和SZ集群调查的离群值。

英文摘要:

Cosmological constraints from cluster surveys rely on accurate mass estimates from the mass-observable relations. In order to avoid systematic biases and reduce uncertainties, we study the form and physical origin of the intrinsic scatter about the mean Sunyaev-Zel'dovich (SZ) flux-mass relation using a hydrodynamical simulation of galaxy cluster formation. We examine the assumption of lognormal scatter and detect non-negligible positive skewness and kurtosis (> 0.5) for a wide range of limiting masses and redshifts. These higher-order moments should be included in the parametrization of scatter in order not to bias cosmological constraints. We investigate the sources of the scatter by correlating it with measures of cluster morphology, halo concentration, and dynamical state, and we quantify the individual contribution from each source. We find that statistically the impact of dynamical state is weak, so the selection bias due to mergers is negligible. On the other hand, there is a strong correlation between the scatter and halo concentration, which can be used to reduce the scatter significantly (from 12.07% to 7.34% or by ~40% for clusters at z = 0). We also show that a cross-calibration by combining information from X-ray followups can be used to reduce the scatter in the flux-mass relation and also identify outliers in both X-ray and SZ cluster surveys.

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