论文标题
NGC 2023中多环芳烃发射的主要成分分析
A Principal Component Analysis of polycyclic aromatic hydrocarbon emission in NGC 2023
论文作者
论文摘要
我们在6.2、7.7、8.6、11.0和11.2 $μ$ m的6.2、7.7、8.6、11.0和11.2 $ $ m的反射Nebula NGC 2023中使用测得的多环芳烃（PAH）发射特征，以进行主成分分析（PCA），作为先前在PAH发射中研究的一种手段。我们发现，几乎所有变体（99％）只能用两个参数来解释 - 前两个主要组件（PC）。我们探讨了这些PC的特性，并表明第一台PC（$ PC_ {1} $）是变化的主要驱动力，代表了PAH的发射量，而PAH的发射量与中性物种占主导地位的电离物种的混合物。第二台PC（$ PC_ {2} $）在整个星云的PAHS的电离状态中追踪变化。 PC与各种PAH比率的相关性表明，6.2和7.7 $ $ m m频段的行为与8.6和11.0 $ $ m m频段的行为不同，从而形成了两组不同的电离频段。我们将PC的空间分布与物理条件进行了比较，特别是辐射场的强度，$ g_ {0} $，以及$ g_ {0}/n_ {h {h} $比率，发现$ pc_ {2} $的变化在$ g _ = $ g_的IOMATID状态下，$ g_ emental（$ g_）aS $ g ement（and）aS proh（and）a imental（and）n emert（AS proh a emert af per a emert af a iment at a emert（a）。 $ pc_ {1} $）不取决于$ g_0 $。
We use the measured fluxes of polycyclic aromatic hydrocarbon (PAH) emission features at 6.2, 7.7, 8.6, 11.0 and 11.2 $μ$m in the reflection nebula NGC 2023 to carry out a principal component analysis (PCA) as a means to study previously reported variations in the PAH emission. We find that almost all of the variations (99%) can be explained with just two parameters -- the first two principal components (PCs). We explore the characteristics of these PCs and show that the first PC ($PC_{1}$), which is the primary driver of the variation, represents the amount of emission of a mixture of PAHs with ionized species dominating over neutral species. The second PC ($PC_{2}$) traces variations in the ionization state of the PAHs across the nebula. Correlations of the PCs with various PAH ratios show that the 6.2 and 7.7 $μ$m bands behave differently than the 8.6 and 11.0 $μ$m bands, thereby forming two distinct groups of ionized bands. We compare the spatial distribution of the PCs to the physical conditions, in particular to the strength of the radiation field, $G_{0}$, and the $G_{0}/n_{H}$ ratio and find that the variations in $PC_{2}$, i.e. the ionization state of PAHs are strongly affected by $G_{0}$ whereas the amount of PAH emission (as traced by $PC_{1}$) does not depend on $G_0$.
