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arXiv 1406.4150astro-ph.GA
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Milky Way - I.从固定势中的模拟重建CO映射

The morphology of the Milky Way - I. Reconstructing CO maps from simulations in fixed potentials

Alex R. Pettitt, Clare L. Dobbs, David M. Acreman, Daniel J. Price

摘要:

我们提出了一个调查的形态特征的银河系。我们使用光滑粒子流体动力学(SPH)来模拟银河系中的星际介质(ISM)的影响下,一些不同的引力势代表旋臂和酒吧,假设银河系是大设计的性质。气体受到ISM冷却和化学作用的影响,使我们能够跟踪分子气体的演化。我们使用一个三维辐射转移代码来模拟从SPH输出的发射,允许从地球上看,合成的光速(l-v)发射图的建设。通过比较这些地图与观测到的银河系中的CO发射,我们推断出臂/棒几何形状,提供了一个最适合我们的银河系。我们发现,它是可能的,重现几乎所有的功能的l-v图中的CO排放。然而,没有一个模型能令人满意地同时再现所有的特征。双臂模型不能再现所有观测到的臂特征,而四臂模型在银河系内部产生太亮的局部发射。我们的最佳拟合模型支持50- 60 km/s/kpc的杆模式速度和大约20 km/s/kpc的臂模式速度,杆方向大约为45度,臂俯仰角在10-15度之间。

英文摘要:

We present an investigation into the morphological features of the Milky Way. We use smoothed particle hydrodynamics (SPH) to simulate the interstellar medium (ISM) in the Milky Way under the effect of a number of different gravitational potentials representing spiral arms and bars, assuming the Milky Way is grand design in nature. The gas is subject to ISM cooling and chemistry, enabling us to track the evolution of molecular gas. We use a 3D radiative transfer code to simulate the emission from the SPH output, allowing for the construction of synthetic longitude-velocity (l-v) emission maps as viewed from the Earth. By comparing these maps with the observed emission in CO from the Milky Way, we infer the arm/bar geometry that provides a best fit to our Galaxy. We find that it is possible to reproduce nearly all features of the l-v diagram in CO emission. There is no model, however, that satisfactorily reproduces all of the features simultaneously. Models with 2 arms cannot reproduce all the observed arm features, while 4 armed models produce too bright local emission in the inner Galaxy. Our best fitting models favour a bar pattern speed within 50-60km/s/kpc and an arm pattern speed of approximately 20km/s/kpc, with a bar orientation of approximately 45 degrees and arm pitch angle between 10-15 degrees.

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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