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arXiv 0911.3302astro-ph.CO
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LoCuSS:20个z~0.2大质量星系团强透镜分析的初步结果

LoCuSS: First Results from Strong-lensing Analysis of 20 Massive Galaxy Clusters at z~0.2

Johan Richard, Graham P. Smith, Jean-Paul Kneib, Richard Ellis, Alastair J. R. Sanderson, Liuyi Pei, Thomas Targett, David Sand, Mark Swinbank, Helmut Dannerbau… 展开作者

Johan Richard, Graham P. Smith, Jean-Paul Kneib, Richard Ellis, Alastair J. R. Sanderson, Liuyi Pei, Thomas Targett, David Sand, Mark Swinbank, Helmut Dannerbauer, Pasquale Mazzotta, Marceau Limousin, Eiichi Egami, Eric Jullo, Victoria Hamilton-Morris, Sean Moran

摘要:

我们提出了一个统计分析的样本20强透镜集群从本地集群子结构调查(LoCuSS),基于高分辨率的哈勃太空望远镜成像的集群核心和后续的光谱观测,使用Spark-I望远镜。我们利用详细的参数化模型计算了团核的质量分布,测量了R<250 kpc的团核总质量和与子结构相关的质量分数,并与由古老的恒星星族和团内X射线辐射介质追踪的团核重子分布进行了比较。我们的主要成果包括:(i)Einstein半径的分布是对数正态分布,峰值和1 σ宽度为<log(RE(z=2))>=1.16+/-0.28;(ii)在3 σ显著性下,我们检测到X射线/透镜质量差异<M_SL/M_X>=1.3--具有较大亚结构分数的团簇显示出更大的质量差异,因此更大地偏离流体静力平衡;(iii)团簇子结构分数也与小尺度上气体密度分布的斜率相关,这意味着团簇-团簇合并和气体冷却之间的联系。总体而言,我们的研究结果是一致的,认为集群集群合并发挥了突出的作用,在塑造集群核心的属性,特别是造成偏离流体静力平衡,并可能干扰冷核心。我们的研究结果不支持最近的说法,大爱因斯坦半径集群提出了一个挑战的CDM范式。

英文摘要:

We present a statistical analysis of a sample of 20 strong lensing clusters drawn from the Local Cluster Substructure Survey (LoCuSS), based on high resolution Hubble Space Telescope imaging of the cluster cores and follow-up spectroscopic observations using the Keck-I telescope. We use detailed parameterized models of the mass distribution in the cluster cores, to measure the total cluster mass and fraction of that mass associated with substructures within R<250kpc.These measurements are compared with the distribution of baryons in the cores, as traced by the old stellar populations and the X-ray emitting intracluster medium. Our main results include: (i) the distribution of Einstein radii is log-normal, with a peak and 1sigma width of <log(RE(z=2))>=1.16+/-0.28; (ii) we detect an X-ray/lensing mass discrepancy of <M_SL/M_X>=1.3 at 3 sigma significance -- clusters with larger substructure fractions displaying greater mass discrepancies, and thus greater departures from hydrostatic equilibrium; (iii) cluster substructure fraction is also correlated with the slope of the gas density profile on small scales, implying a connection between cluster-cluster mergers and gas cooling. Overall our results are consistent with the view that cluster-cluster mergers play a prominent role in shaping the properties of cluster cores, in particular causing departures from hydrostatic equilibrium, and possibly disturbing cool cores. Our results do not support recent claims that large Einstein radius clusters present a challenge to the CDM paradigm.

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