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arXiv 1701.02307astro-ph.CO
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redMaPPer团簇的内禀排列:团簇形状-物质密度相关

Intrinsic alignment of redMaPPer clusters: cluster shape - matter density correlation

Edo van Uitert, Benjamin Joachimi

摘要:

我们测量的星系团的形状对齐,跟踪其卫星分布,与物质密度场使用公共redMapPer目录的基础上SDSS-DR 8,其中包含26 111个集群z~0.6。集群被分成9个红移和丰富度样本;在每个样本中,我们检测到一个积极的对齐,表明集群指向密度峰值。我们解释的潮汐校准范式内的测量,允许的丰富性和红移的依赖。在枢轴红移z=0.3和枢轴丰富度λ=30处的固有排列(IA)幅度为A_{IA} ^{gen}=12.6_{-1.2}^{+1.5}。我们得到初步的证据表明,信号增加向更高的丰富度和较低的红移。我们的测量结果与maxBCG集群和暗物质模拟的结果吻合得很好。将我们的结果与亮红星系的IA测量结果相比较,我们发现星系团的IA振幅形成了一个向更高质量的平滑延伸。这表明这些系统共享一个共同的对齐机制,可以利用它来提高我们对IA的物理理解。

英文摘要:

We measure the alignment of the shapes of galaxy clusters, as traced by their satellite distributions, with the matter density field using the public redMaPPer catalogue based on SDSS-DR8, which contains 26 111 clusters up to z~0.6. The clusters are split into nine redshift and richness samples; in each of them we detect a positive alignment, showing that clusters point towards density peaks. We interpret the measurements within the tidal alignment paradigm, allowing for a richness and redshift dependence. The intrinsic alignment (IA) amplitude at the pivot redshift z=0.3 and pivot richness λ=30 is A_{IA}^{gen}=12.6_{-1.2}^{+1.5}. We obtain tentative evidence that the signal increases towards higher richness and lower redshift. Our measurements agree well with results of maxBCG clusters and with dark-matter-only simulations. Comparing our results to IA measurements of luminous red galaxies, we find that the IA amplitude of galaxy clusters forms a smooth extension towards higher mass. This suggests that these systems share a common alignment mechanism, which can be exploited to improve our physical understanding of IA.

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