标题： 多环芳烃尺寸示踪物 显示英文标题

标题： Polycyclic Aromatic Hydrocarbon Size Tracers

摘要： 我们研究了多环芳烃（PAH）带强度比随平均碳原子数的变化，并评估了它们作为PAH尺寸示踪剂的有效性，利用了NASA艾姆斯PAH红外光谱数据库提供的数据、模型和工具。 为了实现这一目标，我们使用了不同电离分数的PAH混合物的光谱，遵循尺寸分布。 我们的工作与早期发现一致，表明包含3.3 ${\mu}$m PAH带的带强度比对于小到中等尺寸的PAH提供了最佳的PAH尺寸示踪剂。 此外，我们发现包含15-20 ${\mu}$m PAH特征（I$_{\Sigma_{15-20}}$）和6.2或7.7 ${\mu}$m带的带强度比，在对象具有与所呈现模型相似的PAH尺寸分布的情况下，也作为小到中等尺寸PAH的优良示踪剂。 对于不同的PAH尺寸分布，对I$_{6.2}$/I$_{\Sigma_{15-20}}$比值应用缩放因子可以提供源中较小到中等PAH种群的尺寸估计。 就业的 I$_{6.2}$/I$_{\Sigma_{15-20}}$和 I$_{7.7}$/I$_{\Sigma_{15-20}}$比率对于仅限于$\sim$5-28${\mu}$m MIRI(-MRS) 覆盖的JWST观测可能特别有趣。 显示英文摘要

摘要： We examine the dependence of polycyclic aromatic hydrocarbon (PAH) band intensity ratios as a function of the average number of carbon atoms and assess their effectiveness as tracers for PAH size, utilising the data, models, and tools provided by the NASA Ames PAH Infrared Spectroscopic Database. To achieve this, we used spectra from mixtures of PAHs of different ionisation fractions, following a size distribution. Our work, congruent with earlier findings, shows that band ratios that include the 3.3 ${\mu}$m PAH band provide the best PAH size tracers for small-to-intermediate sized PAHs. In addition, we find that band ratios that include the sum of the 15-20 ${\mu}$m PAH features (I$_{\Sigma_{15-20}}$) and the 6.2 or 7.7 ${\mu}$m bands also serve as good tracers for PAH size in the case of small-to-intermediate sized PAHs, for objects under a similar PAH size distribution as with the presented models. For different PAH size distributions, the application of a scaling factor to the I$_{6.2}$/I$_{\Sigma_{15-20}}$ ratio can provide estimates for the size of the small-to-intermediate PAH population within sources. Employment of the I$_{6.2}$/I$_{\Sigma_{15-20}}$ and I$_{7.7}$/I$_{\Sigma_{15-20}}$ ratios can be of particular interest for JWST observations limited only to $\sim$ 5-28 ${\mu}$m MIRI(-MRS) coverage.