论文标题

TNG50模拟中MW样星系的DM光环形态类型:简单,扭曲或拉伸

DM halo morphological types of MW-like galaxies in the TNG50 simulation: Simple, Twisted, or Stretched

论文作者

Emami, Razieh, Genel, Shy, Hernquist, Lars, Alcock, Charles, Bose, Sownak, Weinberger, Rainer, Vogelsberger, Mark, Marinacci, Federico, Loeb, Abraham, Torrey, Paul, Forbes, John C.

论文摘要

我们对TNG50模拟中25个银河系样星系的样本进行了对暗物质(DM)光环的形状的全面分析。使用封闭的体积迭代方法(EVIM),我们通过中位数$ t \ simeq 0.24 $来推断DM晕圈的扁平对三轴形状。我们将DM光晕分为3个不同类别。简单的光环(占人群的32%)建立主轴,其大小的排序不会随半径而变化,并且其方向几乎在整个光环中固定。扭曲的光环(占人群的32%),整个径向轮廓的逐渐旋转水平。最后,拉伸的光环(占人群的36%)在其主要轴长度上表现出拉伸,其中不同特征值随着半径而变化。随后,光环的“旋转”为$ \ sim $ 90°$ 90摄氏度。我们首次将每个光晕的3D椭圆形可视化,我们报告说,在扭曲和拉伸的光环中重新定位椭圆形的迹象。我们通过仅与暗物质(DMO)模拟进行比较,研究了重型物理学对DM光环形状的影响。这表明三轴(珍珠)光环。我们分析了子结构对Hydro和DMO模拟中DM光环形状的影响,并确认它们的影响是亚较大的。我们研究样品中卫星的分布。在简单而扭曲的光环中,卫星的角动量与星系的角动量随着半径而增长。但是,拉伸的光环显示了角度平坦的分布。在文献中提出的观察结果上覆盖我们的理论结果建立了公平的协议。

We present a comprehensive analysis of the shape of dark matter (DM) halos in a sample of 25 Milky Way-like galaxies in TNG50 simulation. Using an Enclosed Volume Iterative Method (EVIM), we infer an oblate-to-triaxial shape for the DM halo with the median $T \simeq 0.24 $. We group DM halos in 3 different categories. Simple halos (32% of population) establish principal axes whose ordering in magnitude does not change with radius and whose orientations are almost fixed throughout the halo. Twisted halos (32% of population), experience levels of gradual rotations throughout their radial profiles. Finally, stretched halos (36% of population) demonstrate a stretching in their principal axes lengths where the ordering of different eigenvalues change with radius. Subsequently, the halo experiences a "rotation" of $\sim$90 deg where the stretching occurs. Visualizing the 3D ellipsoid of each halo, for the first time, we report signs of re-orienting ellipsoid in twisted and stretched halos. We examine the impact of baryonic physics on DM halo shape through a comparison to dark matter only (DMO) simulations. This suggests a triaxial (prolate) halo. We analyze the impact of substructure on DM halo shape in both hydro and DMO simulations and confirm that their impacts are subdominant. We study the distribution of satellites in our sample. In simple and twisted halos, the angle of satellites' angular momentum with galaxy's angular momentum grows with radius. However, stretched halos show a flat distribution of angles. Overlaying our theoretical outcome on the observational results presented in the literature establishes a fair agreement.

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