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arXiv 1503.05563astro-ph.GA
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Milky Way - II的形态。用活恒星分布重建盘星系的CO图

The morphology of the Milky Way - II. Reconstructing CO maps from disc galaxies with live stellar distributions

Alex R. Pettitt, Clare L. Dobbs, David M. Acreman, Matthew R. Bate

摘要:

银河系的臂结构仍然是一个未知数,我们在银河系圆盘内的位置阻碍了观测研究。在这里介绍的工作中,我们使用平滑粒子流体动力学(SPH)和辐射转移,以创建合成的湍流速度观测。我们的目标是通过将合成的光速图与观测到的光速图进行比较,来逆向设计一个自上而下的银河系地图。我们设置了一个N体粒子系统来表示圆盘和凸起,从而可以动态创建螺旋特征。星际气体和分子含量是随着恒星系统演化的。一个3D-辐射转移代码,然后使用比较的模型观测数据。由此产生的模型显示臂的功能,是一个很好的复制许多观测到的银河系的发射结构。然而,这些手臂是动态和瞬态的,允许广泛的形态不可能与标准密度波理论。最佳拟合模型是一个更好的匹配比以前的工作,使用固定电位。他们倾向于一个四臂模型,俯仰角大约为20度,尽管模式速度随着银河半径的增加而降低。然而,缺乏内部的酒吧,这似乎需要完全复制中央分子区。

英文摘要:

The arm structure of the Milky Way remains somewhat of an unknown, with observational studies hindered by our location within the Galactic disc. In the work presented here we use smoothed particle hydrodynamics (SPH) and radiative transfer to create synthetic longitude-velocity observations. Our aim is to reverse-engineer a top down map of the Galaxy by comparing synthetic longitude-velocity maps to those observed. We set up a system of N-body particles to represent the disc and bulge, allowing for dynamic creation of spiral features. Interstellar gas, and the molecular content, is evolved alongside the stellar system. A 3D-radiative transfer code is then used to compare the models to observational data. The resulting models display arm features that are a good reproduction of many of the observed emission structures of the Milky Way. These arms however are dynamic and transient, allowing for a wide range of morphologies not possible with standard density wave theory. The best fitting models are a much better match than previous work using fixed potentials. They favour a 4-armed model with a pitch angle of approximately 20 degrees, though with a pattern speed that decreases with increasing Galactic radius. Inner bars are lacking however, which appear required to fully reproduce the central molecular zone.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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