Group-scale intrinsic galaxy alignments in the Illustris-TNG and MassiveBlack-II simulations
Group-scale intrinsic galaxy alignments in the Illustris-TNG and MassiveBlack-II simulations
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DOI：
10.1093/mnras/staa3934
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发表时间：
2020-02
影响因子：
4.8
通讯作者：
Ananth Tenneti;T. Kitching;B. Joachimi;T. Di Matteo-T.-Di Matteo-1392893525
中科院分区：
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作者：
Ananth Tenneti;T. Kitching;B. Joachimi;T. Di Matteo-T.-Di Matteo-1392893525
我们在MassiveBlack-II （MB-II）和IllustrisTNG模拟中研究了卫星星系的排列及其各向异性分布，以及它们的宿主中心星系的位置和方向。我们发现：质量晕（$\gt 10^{13}\, h^{-1}\, \ maththrm {M}_{\odot}$）的卫星系统的形状与z = 0.06的中央星系的形状很好地对齐，与均匀随机分布相比，长轴之间的平均对齐为~ Δθ = 12°；卫星星系倾向于沿中心星系的长轴各向异性分布，在高质量或高亮度的光晕中有较强的排列；中心星系的卫星分布具有更强的各向异性，其恒星形成率较低，为球形，以及红色中心星系。在径向上，我们发现卫星在较小尺度上倾向于沿中心星系恒星成分形状的长轴分布，而在较大尺度上则倾向于沿暗物质成分形状的长轴分布。我们发现卫星各向异性对中心星系性质和径向距离的依赖在MB-II的两个模拟中相似，振幅更大。在小尺度上，卫星星系的取向倾向于指向中心星系的位置，这种相关性随着距离的增加而降低，并且在大质量晕中，卫星对准的幅度更高。然而，投影的椭圆并不像在一些观测测量中看到的那样，表现出与尺度相关的径向排列。
We study the alignments of satellite galaxies, and their anisotropic distribution, with respect to location and orientation of their host central galaxy in MassiveBlack-II (MB-II) and IllustrisTNG simulations. We find that: the shape of the satellite system in haloes of mass ($\gt 10^{13}\, h^{-1}\, \mathrm{M}_{\odot }$) is well aligned with the shape of the central galaxy at z = 0.06 with the mean alignment between the major axes being ∼Δθ = 12° when compared to a uniform random distribution; that satellite galaxies tend to be anisotropically distributed along the major axis of the central galaxy with a stronger alignment in haloes of higher mass or luminosity; and that the satellite distribution is more anisotropic for central galaxies with lower star formation rate, which are spheroidal, and for red central galaxies. Radially, we find that satellites tend to be distributed along the major axis of the shape of the stellar component of central galaxies at smaller scales and the dark matter component on larger scales. We find that the dependence of satellite anisotropy on central galaxy properties and the radial distance is similar in both the simulations with a larger amplitude in MB-II. The orientation of satellite galaxies tends to point toward the location of the central galaxy at small scales and this correlation decreases with increasing distance, and the amplitude of satellite alignment is higher in high-mass haloes. However, the projected ellipticities do not exhibit a scale-dependent radial alignment, as has been seen in some observational measurements.