Revealing the Ionization Properties of the Magellanic Stream Using Optical Emission
Revealing the Ionization Properties of the Magellanic Stream Using Optical Emission
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DOI：
10.3847/1538-4357/aa992a
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发表时间：
2017-11
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通讯作者：
K. Barger;K. Barger;G. Madsen;Andrew J. Fox;B. Wakker;J. Bland-Hawthorn;D. Nidever;L. M. Haffner;L. M. Haffner;Jacqueline Antwi-Danso;Jacqueline Antwi-Danso;Michael Hernandez;N. Lehner;Alex S. Hill;Alex S. Hill;Andrew Curzons;T. Tepper-García
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作者：
K. Barger;K. Barger;G. Madsen;Andrew J. Fox;B. Wakker;J. Bland-Hawthorn;D. Nidever;L. M. Haffner;L. M. Haffner;Jacqueline Antwi-Danso;Jacqueline Antwi-Danso;Michael Hernandez;N. Lehner;Alex S. Hill;Alex S. Hill;Andrew Curzons;T. Tepper-García
麦哲伦流是一条尾随在麦哲伦云后面的气体尾巴，如果它在蒸发到晕中之前到达银河系盘，就可以用大量的气体补充银河系（MW）。为了确定麦哲伦流的性质如何沿沿着其长度变化，我们进行了观测研究的Hα发射，沿着与其他光学温暖的电离气体示踪剂，向39视线。使用威斯康星州Hα映射望远镜，我们在39条视线中的26条中检测到Hα发射亮度超过30-50 mR。这种Hα发射从H i发射向外延伸。通过与的比较，我们发现，16%-67%的区域是电离的。如果主要的电离源是来自麦哲伦云、MW和河外背景的光电离，那么大部分沿着麦哲伦流的辐射都比预期的要高得多。我们发现，额外的贡献，从自电离通过“冲击级联”的结果，作为流犁通过晕可能足以再现的Hα发射沿着流的基础水平。在南银河系极点以下的稀疏采样区域中，存在一个具有非典型明亮发射的视线子集，这表明气体正在被另一个源进一步电离，该源可能与银河系中心相关的能量过程有关。
The Magellanic Stream, a gaseous tail that trails behind the Magellanic Clouds, could replenish the Milky Way (MW) with a tremendous amount of gas if it reaches the Galactic disk before it evaporates into the halo. To determine how the Magellanic Stream’s properties change along its length, we have conducted an observational study of the Hα emission, along with other optical warm ionized gas tracers, toward 39 sight lines. Using the Wisconsin Hα Mapper telescope, we detect Hα emission brighter than 30–50 mR in 26 of our 39 sight lines. This Hα emission extends over away from the H i emission. By comparing and , we find that regions with are 16%–67% ionized. Most of the along the Magellanic Stream are much higher than expected if the primary ionization source is photoionization from Magellanic Clouds, the MW, and the extragalactic background. We find that the additional contribution from self ionization through a “shock cascade” that results as the Stream plows through the halo might be sufficient to reproduce the underlying level of Hα emission along the Stream. In the sparsely sampled region below the South Galactic Pole, there exists a subset of sight lines with uncharacteristically bright emission, which suggest that gas is being ionized further by an additional source that could be a linked to energetic processes associated with the Galactic center.