Coplanar streams, pancakes and angular‐momentum exchange in high‐z disc galaxies
Coplanar streams, pancakes and angular‐momentum exchange in high‐z disc galaxies
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DOI：
10.1111/j.1365-2966.2012.20751.x
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发表时间：
2011-10
影响因子：
4.8
通讯作者：
M. Danovich;A. Dekel;O. Hahn;R. Teyssier
中科院分区：
文献类型：
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作者：
M. Danovich;A. Dekel;O. Hahn;R. Teyssier
我们使用 Mare Nostrum 水文宇宙学模拟来研究来自宇宙网的流在高红移下对大质量星系的供给。我们的统计样本由 350 个在 z= 2.5 时 ≃1012 M⊙ 的暗物质晕组成。我们发现流入维里半径 Rv 的~70% 是在覆盖维里壳层 10% 的狭窄溪流中。平均 64% 的河流流入量集中在一条河流中，95% 的流入量集中在三个主要河流中。供给巨大光晕的流往往位于从一半到几个 Rv 延伸的平面上，以下称为“流平面”(SP)。这些气流通常嵌入一层薄薄的低熵气体中，即 Zel'dovich 薄饼，它将约 20% 的流入量带入 Rv。宇宙网节点处大质量晕周围的丝平面结构不同于网的大尺度结构，其中丝标记了倾斜片的交叉点。 SP 仅与 Rv 附近的角动量 (AM) 弱对齐，这与通常 80% 的 AM 由一个主导流携带的事实一致。银盘面表现出与大尺度SP垂直的微弱趋势，这与潮汐扭矩理论一致。最有趣的是，圆盘 AM 的方向仅与 Rv 处的 AM 方向相关性较弱。这表明在半径~0.3Rv的“AM球体”内的盘的更大环境中，流和盘之间的界面处存在显着的AM交换。根据该相互作用领域内的扰动形态和运动学，预计所需的大扭矩。这种 AM 交换可能需要也可能不需要对基于 AM 守恒的标准盘建模进行重大修改，具体取决于盘 AM 的幅度受到影响的程度，这还有待研究。
We study the feeding of massive galaxies at high redshift through streams from the cosmic web using the Mare Nostrum hydrocosmological simulation. Our statistical sample consists of 350 dark matter haloes of ≃1012 M⊙ at z= 2.5. We find that ∼70 per cent of the influx into the virial radius Rv is in narrow streams covering 10 per cent of the virial shell. On average 64 per cent of the stream influx is in one stream, and 95 per cent is in three dominant streams. The streams that feed a massive halo tend to lie in a plane that extends from half to a few Rv, hereafter ‘the stream plane’ (SP). The streams are typically embedded in a thin sheet of low-entropy gas, a Zel’dovich pancake, which carries ∼20 per cent of the influx into Rv. The filaments-in-a-plane configuration about the massive haloes at the nodes of the cosmic web differs from the large-scale structure of the web where the filaments mark the intersections of slanted sheets. The SP is only weakly aligned with the angular momentum (AM) near Rv, consistent with the fact that typically 80 per cent of the AM is carried by one dominant stream. The galactic disc plane shows a weak tendency to be perpendicular to the large-scale SP, consistent with tidal-torque theory. Most interesting, the direction of the disc AM is only weakly correlated with the AM direction at Rv. This indicates a significant AM exchange at the interphase between streams and disc in the greater environment of the disc inside an ‘AM sphere’ of radius ∼0.3Rv. The required large torques are expected based on the perturbed morphology and kinematics within this interaction sphere. This AM exchange may or may not require a major modification of the standard disc modelling based on AM conservation, depending on the extent to which the amplitude of the disc AM is affected, which is yet to be studied.