论文标题
基于整个天空的亚MM灰尘发射得出的中间和高速度HI云的灰尘与中性气体比率
Dust-to-neutral gas ratio of the intermediate and high velocity HI clouds derived based on the sub-mm dust emission for the whole sky
论文作者
论文摘要
我们通过对21cm HI发射的多重回归分析进行多重回归分析，结合了子-MM尘埃光学深度。该方法在47Arcmin的分辨率下覆盖了超过80％的天空，并与吸收线测量区分开，向明亮的星系和恒星覆盖了一小部分天空。主要结果包括，IVC的比率在0.1--1.5范围内，模式为0.6（相对于太阳 - 邻次值，同样在以下同样以下），而IVC的大量分数为约20％，包括尘埃贫民气体的比例为<0.5。可以证实，HVC复合物C的50％的比例为<0.3，并且麦哲伦流的比率最低，模式为〜0.1。结果证明，与先前的吸收线测量相反，某些IVC具有低金属气体。考虑到最近的作品表明，IVC与高金属性光环气体相互作用和交换动量，我们认为高金属气体污染了大部分IVC。因此，我们认为，IVC包括从星系外提供的低金属气体的很大一部分，作为银河形象模型的替代方案。
We derived the dust-to-HI ratio of the intermediate-velocity clouds (IVCs), the high-velocity clouds (HVCs), and the local HI gas, by carrying out a multiple-regression analysis of the 21cm HI emission combined with the sub-mm dust optical depth. The method covers over 80 per cent of the sky contiguously at a resolution of 47arcmin and is distinguished from the absorption line measurements toward bright galaxies and stars covering a tiny fraction of the sky. Major results include that the ratio of the IVCs is in a range of 0.1--1.5 with a mode at 0.6 (relative to the solar-neighbourhood value, likewise below) and that a significant fraction, ~20 per cent, of the IVCs include dust-poor gas with a ratio of <0.5. It is confirmed that 50 per cent of the HVC Complex C has a ratio of <0.3, and that the Magellanic Stream has the lowest ratio with a mode at ~0.1. The results prove that some IVCs have low metallicity gas, contrary to the previous absorption line measurements. Considering that the recent works show that the IVCs are interacting and exchanging momentum with the high-metallicity Galactic halo gas, we argue that the high-metallicity gas contaminates a significant fraction of the IVCs. Accordingly, we argue that the IVCs include a significant fraction of the low metallicity gas supplied from outside the Galaxy as an alternative to the Galactic-fountain model.
