| 宇宙大尺度结构对星系形成和空间排列的影响 |
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| 引用本文： | 王鹏.宇宙大尺度结构对星系形成和空间排列的影响[J].天文学报,2021,62(1):11-119. |
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| 作者姓名： | 王鹏 |
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| 作者单位： | 中国科学院紫金山天文台 南京 210023 |
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| 摘 要： | 星系的空间排列以及指向并非随机的.星系的主轴和角动量与物质的大尺度分布存在一定的指向相关.这一方向的研究将可以促进我们对结构形成机制的认识,并提供一个独立的视角去检验星系形成过程中的环境效应.本文就相关问题做了详细的探讨.
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| 关 键 词： | 宇宙大尺度结构 星系形成 空间排列 尺度分布 环境效应 角动量 |
The Large Scale Structure of the Universe and Its Impact on Galaxy Formation and Spatial Alignment |
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| WANG Peng.The Large Scale Structure of the Universe and Its Impact on Galaxy Formation and Spatial Alignment[J].Acta Astronomica Sinica,2021,62(1):11-119. |
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| Authors: | WANG Peng |
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| Institution: | Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210023 |
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| Abstract: | The spatial distribution and orientation of galaxies are not random. The direction of galaxy shape and spin are correlated with the direction of the distribution of mass on large scale. Research in this field will promote our understanding of the mechanism of structure formation and provide an independent perspective to examine the environmental effects of galaxies formation. We have discussed in detail with related issues. First of all, we introduced an improved algorithm of classifying the large scale structure. We then investigated the accretion history of dark matter halos in large scale structure. We studied the tendency of accretion relative to halo''s shapes and large scale structure. We find that subhalos tend to be accreted along the direction of the major axis of the host halo. This accretion pattern is universal and depends on the virial mass of the host halo. We also find that the accretion relative to the direction of large scale (the slowest direction of material collapse) is not universal. Low-mass host halos tend to accrete subhaloes from the direction that''s perpendicular to the direction of large scale structure, while high-mass hosts tend to accrete subhaloes from the direction that is aligned with the direction of large scale structure. This ``two-stage'' accretion mode breaks the ``only parallel'' accretion mode suggested in previous works, providing a solution to the problem of halo spin-flip. Additionally, we also studied the formation and evolution of the correlation between the halo spin and the direction of the large scale structure (spin-LSS). We find that the spin flips are not only occurring in filaments but also in knots. For halos in filament, the spin-LSS correlation is related to their formation time, migration time and mass growth rate. We further found that, statistically, all halos have their spins aligned with the direction of LSS at the very early time, and then gradually evolve toward the vertical direction. High-mass halo evolves fast, while low-mass halo evolves slowly. Therefore, at $z=0$, low-mass halo still shows a parallel trend while high-mass halo shows a vertical trend. This evolution pattern depends on the mass accretion history during halo formation. At last, the correlation between galaxy spin and the large scale tidal field is investigated. We mainly find that the spins of low-mass, blue, oblate galaxies are preferentially parallel to the direction of the large scale tidal field, while the spins of high-mass, red, prolate galaxies tend to be perpendicular to the direction of the large scale tidal field. Of these three properties, galaxy stellar mass is the main factor. The transition from parallel to perpendicular trend occurs at about $10^{9.4}\msun$ in the stellar mass, $\sim 0.62$ in g-r color, and $\sim 0.4$ in triaxiality. |
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