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arXiv 1105.3477astro-ph.CO
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等级宇宙中的大质量红色星系--II极红天体的成簇

Massive, red galaxies in a hierarchical universe-II Clustering of Extremely Red Objects

V. Gonzalez-Perez, C. M. Baugh, C. G. Lacey, J. -W. Kim

摘要:

利用半解析星系形成模型结合宇宙学N体模拟,对Λ冷暗物质宇宙中极红天体(ERO)的成簇进行了预测. ERO是在0.7< z < 3观测到的红色大质量星系,它们的数量和性质对分层星系形成模型提出了挑战。分析了ERO的晕占据分布和两点关联函数,探讨了这些量随视星等、色切和红移的变化规律。我们的模型预测的晕占据分布是显着不同的,通常假设。这是由于活动星系核反馈的加入,它改变了活动星系核反馈第一次变得重要的质量之上的亮度-宿主晕质量关系的斜率和散射。我们预测,平均而言,质量大于10^{13}h^{-1}Msun的暗物质晕至少有一个在1.5 < z < 2.5处的ERO。考虑到观测估计中的样本方差,对于(R-K)>5或(i-K)>4.5的ERO,预测的角聚类与当前观测结果相当一致。

英文摘要:

We present predictions for the clustering of Extremely Red Objects (EROs) in a Λcold dark matter Universe, using a semi-analytical galaxy formation model in combination with a cosmological N-body simulation. EROs are red, massive galaxies observed at 0.7< z < 3, and their numbers and properties have posed a challenge to hierarchical galaxy formation models. We analyse the halo occupation distribution and two-point correlation function of EROs, exploring how these quantities change with apparent magnitude, colour cut and redshift. Our model predicts a halo occupation distribution that is significantly different from that typically assumed. This is due to the inclusion of AGN feedback, which changes the slope and scatter of the luminosity-host halo mass relation above the mass where AGN feedback first becomes important. We predict that, on average, dark matter haloes with masses above 10^{13}h^{-1}Msun host at least one ERO at 1.5 < z < 2.5. Taking into account sample variance in observational estimates, the predicted angular clustering for EROs with either (R-K)>5 or (i-K)>4.5 is in reasonable agreement with current observations.

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