DETECTION OF THE SPLASHBACK RADIUS AND HALO ASSEMBLY BIAS OF MASSIVE GALAXY CLUSTERS
DETECTION OF THE SPLASHBACK RADIUS AND HALO ASSEMBLY BIAS OF MASSIVE GALAXY CLUSTERS
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DOI：
10.3847/0004-637x/825/1/39
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发表时间：
2016-01
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通讯作者：
S. More;H. Miyatake;M. Takada;B. Diemer;A. Kravtsov;N. Dalal;A. More;Ryoma Murata;R. Mandelbaum;E. Rozo;E. Rykoff;M. Oguri;D. Spergel
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作者：
S. More;H. Miyatake;M. Takada;B. Diemer;A. Kravtsov;N. Dalal;A. More;Ryoma Murata;R. Mandelbaum;E. Rozo;E. Rykoff;M. Oguri;D. Spergel
我们发现，斯隆数字巡天光度星系周围的星系团的投影数密度分布显示强有力的证据的溅回半径，一个尖锐的晕边缘对应的卫星星系的第一个轨道远心的位置后，他们的陷落。我们将星系团分成两个子样本，在固定的丰度和红移下，它们的成员具有不同的平均投影径向距离。样品与较小的有一个较小的比例的回溅半径传统的晕边界比子样品与较大的，指示不同的质量吸积率为这些子样品。Miyatake等人最近使用了相同的子样本，以表明尽管它们具有相似的弱透镜质量，但它们的大规模聚类不同，这证明了晕组装偏差的强有力证据。我们扩展了这一结果，提出了一个6.6σ的差异，这些样本的集群振幅使用集群光度星系互相关。这一测量结果清楚地表明，晕簇取决于晕质量以外的参数。如果与晕的质量组装历史有关，则测量是晕组装偏差的一种表现。然而，我们测得的回溅半径较小，而组件偏置信号的强度较强，比无碰撞Λ冷暗物质模拟的预测。我们表明，动力学摩擦，集群错位，或投影效应不太可能是这些差异的唯一来源。然而，关于未知的灾难性弱透镜或集群识别系统学的进一步调查是必要的。
We show that the projected number density profiles of Sloan Digital Sky Survey photometric galaxies around galaxy clusters display strong evidence for the splashback radius, a sharp halo edge corresponding to the location of the first orbital apocenter of satellite galaxies after their infall. We split the clusters into two subsamples with different mean projected radial distances of their members, , at fixed richness and redshift. The sample with smaller has a smaller ratio of the splashback radius to the traditional halo boundary than the subsample with larger , indicative of different mass accretion rates for these subsamples. The same subsamples were recently used by Miyatake et al. to show that their large-scale clustering differs despite their similar weak lensing masses, demonstrating strong evidence for halo assembly bias. We expand on this result by presenting a 6.6σ difference in the clustering amplitudes of these samples using cluster–photometric galaxy cross-correlations. This measurement is a clear indication that halo clustering depends on parameters other than halo mass. If is related to the mass assembly history of halos, the measurement is a manifestation of the halo assembly bias. However, our measured splashback radii are smaller, while the strength of the assembly bias signal is stronger, than the predictions of collisionless Λ cold dark matter simulations. We show that dynamical friction, cluster mis-centering, or projection effects are not likely to be the sole source of these discrepancies. However, further investigations regarding unknown catastrophic weak lensing or cluster identification systematics are warranted.