模拟团簇质温关系中的子结构和散射
Substructure and Scatter in the Mass-Temperature Relations of Simulated Clusters
摘要：
星系团的整体性质之间存在着规律性的标度关系。这些关系建立晕质量和集群观测之间的重要联系。精确的宇宙学研究，依赖于这些联系受益于更好地理解散射的质量可观测的标度关系。在这里，我们研究的合并过程中引入散射的$M$ - $T_{\rm X}$关系的作用，使用的样本121个星系团模拟辐射冷却和超新星反馈，以及三个统计先前提出的测量X射线表面亮度子结构。它们是形心变化（$w$）、轴比（$η$）和功率比（$P_{20}$和$P_{30}$）。我们发现，在这一组模拟集群，每个子结构措施与集群的偏离$δ\ln T_{\rm X}$和$δ\ln M$从平均$M$ - $T_{\rm X}$关系，无论是发射加权温度$T_{\rm EW}$和光谱般的温度$T_{\rm SL}$，在这个意义上，具有更多的子结构的集群往往是在一个给定的晕质量更冷。在所有情况下，对包括子结构信息的$M$ - $T_{\rm X}$关系的三参数拟合比对基本$M$ - $T_{\rm X}$关系的两参数拟合具有更小的分散性。
英文摘要：
Galaxy clusters exhibit regular scaling relations among their bulk properties. These relations establish vital links between halo mass and cluster observables. Precision cosmology studies that depend on these links benefit from a better understanding of scatter in the mass-observable scaling relations. Here we study the role of merger processes in introducing scatter into the $M$-$T_{\rm X}$ relation, using a sample of 121 galaxy clusters simulated with radiative cooling and supernova feedback, along with three statistics previously proposed to measure X-ray surface brightness substructure. These are the centroid variation ($w$), the axial ratio ($η$), and the power ratios ($P_{20}$ and $P_{30}$). We find that in this set of simulated clusters, each substructure measure is correlated with a cluster's departures $δ\ln T_{\rm X}$ and $δ\ln M$ from the mean $M$-$T_{\rm X}$ relation, both for emission-weighted temperatures $T_{\rm EW}$ and for spectroscopic-like temperatures $T_{\rm SL}$, in the sense that clusters with more substructure tend to be cooler at a given halo mass. In all cases, a three-parameter fit to the $M$-$T_{\rm X}$ relation that includes substructure information has less scatter than a two-parameter fit to the basic $M$-$T_{\rm X}$ relation.
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