The evolution of assembly bias
The evolution of assembly bias
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DOI：
10.1093/mnras/stz018
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发表时间：
2018-08
影响因子：
4.8
通讯作者：
S. Contreras;I. Zehavi;Nelson Padilla;C. Baugh;Esteban Jim'enez;I. Lacerna
中科院分区：
文献类型：
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作者：
S. Contreras;I. Zehavi;Nelson Padilla;C. Baugh;Esteban Jim'enez;I. Lacerna
我们使用 Millennium-WMAP7 N 体模拟中实现的星系形成的半解析模型来研究组装偏差的演变。我们考虑按恒星质量或恒星形成率排名的固定数量密度星系样本。我们研究了晕的聚集及其星系内容如何取决于晕的形成时间和浓度，以及这些关系如何随着红移而演变。在 z = 0 时，晕簇对晕浓度和形成时间的依赖性是相似的。在红移较高时，按年龄选择的光晕的光晕组装偏差会减弱，而按浓度选择的光晕则相反并增加，这与之前的研究一致。晕占据随浓度和形成时间的变化在 z = 0 时也相似，并且在较高红移时发生变化。在这里，占用率随光晕年龄的变化在红移时基本保持不变，但随着浓度的变化而减小。最后，我们通过检查相对于消除占据变化的洗牌星系样本的星系相关函数来观察星系分布中反映的组装偏差的演变。这种相关函数比率随着较大的红移和较低的数量密度样本而单调减小，在某些情况下低于统一，导致星系聚类减少。虽然晕占据函数本身有所不同，但无论是通过恒星质量还是恒星形成率来选择星系，组装偏差趋势都是相似的。我们的结果进一步深入了解装配偏差的起源和演变。我们广泛的职业功能测量和拟合是公开的，可用于创建逼真的模拟目录。
We examine the evolution of assembly bias using a semi-analytical model of galaxy formation implemented in the Millennium-WMAP7 N-body simulation. We consider fixed number density galaxy samples ranked by stellar mass or star formation rate. We investigate how the clustering of haloes and their galaxy content depend on halo formation time and concentration, and how these relationships evolve with redshift. At z = 0 the dependences of halo clustering on halo concentration and formation time are similar. At higher redshift, halo assembly bias weakens for haloes selected by age, and reverses and increases for haloes selected by concentration, consistent with previous studies. The variation of the halo occupation with concentration and formation time is also similar at z = 0 and changes at higher redshifts. Here, the occupancy variation with halo age stays mostly constant with redshift but decreases for concentration. Finally, we look at the evolution of assembly bias reflected in the galaxy distribution by examining the galaxy correlation functions relative to those of shuffled galaxy samples that remove the occupancy variation. This correlation functions ratio monotonically decreases with larger redshift and for lower number density samples, going below unity in some cases, leading to reduced galaxy clustering. While the halo occupation functions themselves vary, the assembly bias trends are similar whether selecting galaxies by stellar mass or star formation rate. Our results provide further insight into the origin and evolution of assembly bias. Our extensive occupation function measurements and fits are publicly available and can be used to create realistic mock catalogues.