arXiv 1611.003662016-11astro-ph.CO

关于SDSS中的簇装配偏差水平

On the Level of Cluster Assembly Bias in SDSS

Ying Zu, Rachel Mandelbaum, Melanie Simet, Eduardo Rozo, Eli S. Rykoff

备注：: 11 pages, 8 figures, MNRAS published
DOI：: 10.1093/mnras/stx1264

摘要：

最近，几项研究发现了一个强烈的差异大规模的聚类偏差的两个子样本的星系团在相同的晕质量，分裂的平均投影成员距离$R_{\mathrm{mem}}$。这种差异的水平显着超过了最大的光环组件偏置信号LCDM预测。在这项研究中，我们探讨是否有一些聚类偏差的差异可能会造成的偏见$R_{\mathrm{mem}}$由于投影效果从其他系统沿视线。我们彻底调查晕组装偏差的光度检测redMapper集群在SDSS中，通过定义一个新的变种的平均成员距离估计$\tilde{R}_{\mathrm{mem}}$，这是更强大的对投影效应的集群成员身份识别。利用星系团的角标记关联函数，我们证明了在用$R_{\mathrm{mem}}$分裂时的大尺度偏差差异在很大程度上可以归因于这种投影效应。在通过$\tilde{R}_{\mathrm{mem}}$分裂之后，极大的信号被减小，从而给出如从弱透镜测量的两个聚类偏差之间的比率$1.02\pm0.14$。使用一个现实的模拟集群目录，我们预测，两个$\tilde{R}_{\mathrm{mem}}$分裂的子样本之间的偏差比应该是$<1.10$，这是至少60%弱于最大晕组装偏差信号（1.24）时，分裂晕浓度。因此，我们的研究结果表明，在SDSS中redMapPer集群所表现出的晕组装偏差的水平是一致的LCDM预测。随着集群数量增加十倍，更深入的持续调查将能够更强大地检测晕组装偏差。我们的研究结果也有重要的影响，如何投影效应和它们对集群宇宙学的影响可以量化测光集群目录。

英文摘要：

Recently, several studies have discovered a strong discrepancy between the large-scale clustering biases of two subsamples of galaxy clusters at the same halo mass, split by their average projected membership distances $R_{\mathrm{mem}}$. The level of this discrepancy significantly exceeds the maximum halo assembly bias signal predicted by LCDM. In this study, we explore whether some of the clustering bias differences could be caused by biases in $R_{\mathrm{mem}}$ due to projection effects from other systems along the line-of-sight. We thoroughly investigate the halo assembly bias of the photometrically-detected redMaPPer clusters in SDSS, by defining a new variant of the average membership distance estimator $\tilde{R}_{\mathrm{mem}}$ that is more robust against projection effects in the cluster membership identification. Using the angular mark correlation functions of clusters, we show that the large-scale bias differences when splitting by $R_{\mathrm{mem}}$ can be largely attributed to such projection effects. After splitting by $\tilde{R}_{\mathrm{mem}}$, the anomalously large signal is reduced, giving a ratio of $1.02\pm0.14$ between the two clustering biases as measured from weak lensing. Using a realistic mock cluster catalog, we predict that the bias ratio between two $\tilde{R}_{\mathrm{mem}}$-split subsamples should be $<1.10$, which is at least 60% weaker than the maximum halo assembly bias signal (1.24) when split by halo concentration. Therefore, our results demonstrate that the level of halo assembly bias exhibited by redMaPPer clusters in SDSS is consistent with the LCDM prediction. With a ten-fold increase in cluster numbers, deeper ongoing surveys will enable a more robust detection of halo assembly bias. Our findings also have important implications for how projection effects and their impact on cluster cosmology can be quantified in photometric cluster catalogs.

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摘要：

英文摘要：

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