论文标题
λ21-cm星际hi轮廓的高斯分解
Gaussian Decomposition of λ21-cm Interstellar HI profiles
论文作者
论文摘要
遵循建立的科学方案，必须可重现该结果，我们检查了通过两种看似互补的方法获得的银河21厘米发射曲线的高斯拟合：基于Verschuur（2004）和Nidever等人的自动化技术所使用的方法，通过两种看似互补的方法获得了半自动化方法。 （2008）。两种方法都使用莱顿/阿根廷/波恩全套调查中的数据。自动化例程的吸引力是很棒的，即使没有其他原因除了在半自动拟合中节省的时间。但是，陷阱通常是意外的，任何算法的最重要方面是结果的可重复性。比较导致Nidever等人对四个问题的识别。 （2008）分析：（1）计算减少的卡方测量拟合优度的不同方法； （2）一个超大的组件发现弥合了低速和中间速度气体之间的间隙； （3）缺乏施加的空间相干性，允许不同的组件出现并消失在梁宽度的一小部分分离的剖面中； （4）在北部银河两极的剖面上，多种材料的多种解决方案。两步方法将改善该算法，在该算法中，自动化拟合随后是质量 - 贴合，视觉检查。这项研究从这项对线条宽度为34 km/s的普遍成分的研究中得出了证实，这可以通过氦气的临界电离速度（CIV）来解释。由于Nidever等。 （2008）论文包含与CIV模型相矛盾的被驳回文献中唯一的结果，重要的是要了解分析中的缺陷，这使这一矛盾。
Following an established protocol of science, that results must be reproducible, we examine the Gaussian fits to Galactic 21-cm emission profiles obtained by two seemingly complementary methods: the semi-automated approach based on the method used by Verschuur (2004) and the automated technique of Nidever et al. (2008). Both methods use data from the Leiden/Argentine/Bonn all-sky survey. The appeal of an automated routine is great, if for no other reason than the time saved over semi-automated fits. The pitfalls, however, are often unanticipated, and the most important aspect of any algorithm is the reproducibility of the results. The comparisons led to the identification of four problems with the Nidever et al. (2008) analysis: (1) different methods of calculating the reduced chi-squared measuring the goodness of fit; (2) an ultra-broad component found bridging the gap between low and intermediate velocity gas; (3) the lack of an imposed spatial coherence allowing different components to appear and disappear in profiles separated by a fraction of a beam width; and (4) multiple, fundamentally different solutions for the profiles at both the North and South Galactic Poles. A two-step method would improve the algorithm, where an automated fit is followed by a quality-assurance, visual inspection. Confirming evidence emerges from this study of a pervasive component with a line width of order 34 km/s, which may be explained by the Critical Ionization Velocity (CIV) of helium. Since the Nidever et al. (2008) paper contains the only result in the refereed literature that contradicts the CIV model, it is important to understand the flaws in the analysis that let to this contradiction.
