288个大质量星系团动力学状态的SZ-X射线-光学联合分析
A joint SZ-Xray-optical analysis of the dynamical state of 288 massive galaxy clusters
摘要：
我们使用暗能量巡天前三年的图像来描述南极望远镜（SPT）Sunyaev-Zeldovich（SZ）效应巡天（SPT-SZ）探测到的$0.1 \lesssim z \lesssim 0.9$上288个星系团的动力学状态。我们研究最亮的星系团（BCG）的位置和气体分布的中心之间的空间偏移跟踪的SPT-SZ质心和X射线质心/峰位置从钱德拉和XMM数据。我们发现，径向分布的偏移量没有提供任何证据表明，SPT SZ选择的集群样本包括一个更高的分数比X射线选择的集群样本的合并。我们使用的偏移分类的集群的动态状态，选择43个最受干扰的集群，其中一半在$z \gtrsim 0.5$，一个地区以前很少探索。我们发现Schechter函数对扰动星系团和弛豫星系团中星系人口的拟合在$z>0.55$处不同，但在较低的红移处不一样。在$z>0.55$的扰动星团有更陡的暗端斜率和更亮的特征星等。在相同的红移范围内，我们发现弛豫团簇中的BCGs往往比扰动样品中的BCGs更亮，而在较低的红移区间内则一致。可能的解释包括更高的合并率，以及在高红移时更有效的动力学摩擦。红序星系的人口比一般的星系人口受星系团动力学状态的影响要小。
英文摘要：
We use imaging from the first three years of the Dark Energy Survey to characterize the dynamical state of 288 galaxy clusters at $0.1 \lesssim z \lesssim 0.9$ detected in the South Pole Telescope (SPT) Sunyaev-Zeldovich (SZ) effect survey (SPT-SZ). We examine spatial offsets between the position of the brightest cluster galaxy (BCG) and the center of the gas distribution as traced by the SPT-SZ centroid and by the X-ray centroid/peak position from Chandra and XMM data. We show that the radial distribution of offsets provides no evidence that SPT SZ-selected cluster samples include a higher fraction of mergers than X-ray-selected cluster samples. We use the offsets to classify the dynamical state of the clusters, selecting the 43 most disturbed clusters, with half of those at $z \gtrsim 0.5$, a region seldom explored previously. We find that Schechter function fits to the galaxy population in disturbed clusters and relaxed clusters differ at $z>0.55$ but not at lower redshifts. Disturbed clusters at $z>0.55$ have steeper faint-end slopes and brighter characteristic magnitudes. Within the same redshift range, we find that the BCGs in relaxed clusters tend to be brighter than the BCGs in disturbed samples, while in agreement in the lower redshift bin. Possible explanations includes a higher merger rate, and a more efficient dynamical friction at high redshift. The red-sequence population is less affected by the cluster dynamical state than the general galaxy population.
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