星系团质温关系中浓度和动力学状态对散射的影响
The Influence of Concentration and Dynamical State on Scatter in the Galaxy Cluster Mass-Temperature Relation
摘要：
利用流体力学加N体方法模拟大体积星系团的形成过程，并结合模拟Chandra X射线观测，研究了星系团最佳拟合X射线温度-质量关系的内禀散射的形成和演化.我们调查的物理起源的散射相关的数量是密切相关的集群的形成和合并的历史。我们还研究了分散合并和nonmerging人口的分布，确定使用晕合并来自模拟以及X射线子结构措施的树木。我们发现在M-T_X关系中的散射和晕的浓度之间有很强的相关性，在这个意义上，更集中的集群往往比具有类似质量的集群更冷。在合并和松弛的团簇之间没有发现偏差，但是合并的团簇通常具有更大的分散性，这与晕浓度分布的性质有关。我们还检测到一个签名的非对数正态分布的散射我们的模拟集群在z=0和z=1。在讨论中给出了由子结构测度和晕合并树确定的合并簇的详细比较。我们的结论是，当冷却相关的影响被忽略，晕浓度的变化是一个更重要的因素驱动的内在散射的M-T_X关系，而偏离流体静力学平衡，由于集群合并有一个较小的影响。
英文摘要：
Using a hydrodynamics plus N-body simulation of galaxy cluster formation within a large volume and mock Chandra X-ray observations, we study the form and evolution of the intrinsic scatter about the best-fit X-ray temperature-mass relation for clusters. We investigate the physical origin of the scatter by correlating it with quantities that are closely related to clusters' formation and merging histories. We also examine the distribution of the scatter for merging and nonmerging populations, identified using halo merger trees derived from the simulation as well as X-ray substructure measures. We find a strong correlation between the scatter in the M-T_X relation and the halo concentration, in the sense that more concentrated clusters tend to be cooler than clusters with similar masses. No bias is found between the merging and relaxed clusters, but merging clusters generally have greater scatter, which is related to the properties of the distribution of halo concentrations. We also detect a signature of non-lognormality in the distribution of scatter for our simulated clusters both at z=0 and at z=1. A detailed comparison of merging clusters identified by substructure measures and by halo merger trees is given in the discussion. We conclude that, when cooling-related effects are neglected, the variation in halo concentrations is a more important factor for driving the intrinsic scatter in the M-T_X relation, while departures from hydrostatic equilibrium due to cluster mergers have a minor effect.
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