Connecting the cosmic web to the spin of dark haloes: implications for galaxy formation
Connecting the cosmic web to the spin of dark haloes: implications for galaxy formation
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DOI：
10.1111/j.1365-2966.2012.21636.x
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发表时间：
2012-01
影响因子：
4.8
通讯作者：
S. Codis;C. Pichon;J. Devriendt;A. Slyz;D. Pogosyan;Y. Dubois;T. Sousbie
中科院分区：
文献类型：
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作者：
S. Codis;C. Pichon;J. Devriendt;A. Slyz;D. Pogosyan;Y. Dubois;T. Sousbie
我们研究了暗物质晕的自旋相对于(i)周围大尺度丝状结构和（ii）潮汐张量特征向量的排列，使用地平线4π暗物质模拟，该模拟在红移为零时解析了超过4300万个暗物质晕。我们检测到一个清晰的大规模转型:自旋的暗物质晕超过临界massM s 10 0≈5(±1)�12 M⊙往往是垂直于最近的大规模灯丝(超额概率高达12%),并与中间的轴潮汐张量(与过量的概率高达40%),而低质量的自旋晕是更有可能与最近的灯丝(超额概率高达15%)。此外，该临界质量与红移有关，标度为M s (z)≈M s′(1 +z)−γs，其中γs = 2.5±0.2。潮汐张量跃迁质量的红移演化近似拟合得到M t≈8（±2）−10 12 M⊙和γt = 3±0.3。这个临界质量也随定义细丝的尺度变化不大。我们从大尺度宇宙流的角度对这个信号提出了一种解释。在这张图中，大多数低质量光晕是通过嵌入在错位壁上的缠绕流形成的；因此，它们的自旋与在这些壁的交叉处形成的细丝的轴线平行。另一方面，更大质量的光晕通常是后来沿着这些细丝合并的产物，因此当它们的轨道角动量转换为自旋时，它们获得垂直于这个方向的自旋。我们的研究表明，这种情况与测量到的额外对准概率、潮汐张量的本征方向和光晕合并历史是一致的。在更定性的层面上，它似乎也与“平滑”暗物质模拟或气体示踪粒子追踪的宇宙网结构的3D可视化兼容。最后，它为Pichon et al.（2011）提出的星系盘形成范式提供了额外的支持，因为它通过描述高红移的二次落入的几何形状来扩展它。
We investigate the alignment of the spin of dark matter halos relative (i) to the surrounding large-scale filamentary structure, and (ii) to the tidal tensor eigenvectors using the Horizon 4π dark matter simulation which resolves over 43 million dark matter halos at redshift zero. We detect a clear mass transition: the spin of dark matter halos above a critical massM s 0 ≈ 5(±1) �10 12 M⊙ tends to be perpendicular to the closest large scale filament (with an excess probability up to 12%), and aligned with the intermediate axis of the tidal tensor (with an excess probability of up to 40%), whereas the spin of low-mass halos is more likely to be aligned with the closest filament (with an excess probability up to 15%). Furthermore, this critical mass is redshift-dependent, scaling as M s (z) ≈ M s �(1 +z) −γs with γs = 2.5 ± 0.2. A similar fit for the redshift evolution of the tidal tensor transition mass yields M t ≈ 8(±2) �10 12 M⊙ and γt = 3 ± 0.3. This critical mass also varies weakly with the scale defining filaments. We propose an interpretation of this signal in terms of large-scale cosmic flows. In this picture,most low-mass halos areformed through the winding offlows embedded in misaligned walls; hence they acquire a spin parallel to the axis of the resulting filaments forming at the intersection of these walls. On the other hand, more massive halos are typically the products of later mergers along such filaments, and thus they acquire a spin perpendicular to this direction when their orbital angular momentum is converted into spin. We show that this scenario is consistent with both the measured excess probabilities of alignment w.r.t. the eigen-directions of the tidal tensor, and halo merger histories. On a more qualitative level, it also seems compatible with 3D visualization of the structure of the cosmic web as traced by “smoothed” dark matter simulations or gas tracer particles. Finally, it provides extra support to the disc forming paradigm presented by Pichon et al. (2011) as it extends it by characterizing the geometry of secondary infall at high redshift.