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arXiv 1002.1964astro-ph.CO
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圆盘Galerkin的大尺度取向

The Large-Scale Orientations of Disk Galaxies

Oliver Hahn, Romain Teyssier, C. Marcella Carollo

备注：
18 pages, 17 figures. Accepted for publication in MNRAS. A high-resolution version available at http://www.slac.stanford.edu/~hahn/pub/HahnTeyssierCarollo2010.pdf
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摘要：

我们使用380 h-1 pc分辨率的流体动力学AMR模拟的宇宙细丝调查的方向的样本的100个良好分辨星系盘跨越两个数量级的恒星和晕质量。我们发现：（i）在z=0时，在星系盘所在的内暗物质晕区域，在气态和恒星星系盘的自旋矢量与其内宿主晕的自旋矢量之间，存在一个几乎完美的18度中位角对准。然而，星系自旋和整个宿主晕自旋之间的对齐明显较弱，范围从z=1时的~46度到z=0时的~50度。(ii)质量最大的星系盘有优先排列的自旋，以便沿着它们的主丝指向。(iii)低质量晕盘的自旋显示，在红移z~0.5以上和低环境密度的地区，与大尺度潮汐场的中间主轴对齐的明显标志。这种行为与线性潮汐力矩理论的预测是一致的。这种排列随着环境密度的增加而减少，并且在最高密度区域中消失。高密度环境中的非线性效应是建立这种密度-排列相关性的必然原因。我们希望我们的数值结果提供了重要的见解，无论是从天体物理的角度理解弱透镜的内在排列和宇宙学背景下的星系盘的形成和演化过程。

英文摘要：

We use a 380 h-1 pc resolution hydrodynamic AMR simulation of a cosmic filament to investigate the orientations of a sample of ~100 well-resolved galactic disks spanning two orders of magnitude in both stellar and halo mass. We find: (i) At z=0, there is an almost perfect alignment at a median angle of 18 deg, in the inner dark matter halo regions where the disks reside, between the spin vector of the gaseous and stellar galactic disks and that of their inner host haloes. The alignment between galaxy spin and spin of the entire host halo is however significantly weaker, ranging from a median of ~46 deg at z=1 to ~50 deg at z=0. (ii) The most massive galaxy disks have spins preferentially aligned so as to point along their host filaments. (iii) The spin of disks in lower-mass haloes shows, at redshifts above z~0.5 and in regions of low environmental density, a clear signature of alignment with the intermediate principal axis of the large-scale tidal field. This behavior is consistent with predictions of linear tidal torque theory. This alignment decreases with increasing environmental density, and vanishes in the highest density regions. Non-linear effects in the high density environments are plausibly responsible for establishing this density-alignment correlation. We expect that our numerical results provide important insights for both understanding intrinsic alignment in weak lensing from the astrophysical perspective and formation and evolution processes of galactic disks in a cosmological context.

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