论文标题
塞弗特和星形星系中的多环芳族烃
Polycyclic Aromatic Hydrocarbons in Seyfert and star-forming galaxies
论文作者
论文摘要
多环芳烃（PAHS）是由芳族环和相关物种结合而产生的碳基分子，它们可能是强大的红外发射特征（3.3、6.2、7.7、8.6、11.3和12.7微米）。在这项工作中，使用50个Seyfert星系（DL <100 MPC）样品，我们比较了AGN的周环（内部KPC）PAH发射与恒星形成星系的对照样品（22个发光的红外星系和30个HII Galaxies），并研究中央和扩展PAH PAH之间的差异。使用Seyfert和Star形成星系的Spitzer/红外光谱光谱数据以及新开发的PAH诊断模型网格，源自理论光谱，我们比较了预测和观察到的PAH比率。我们发现，恒星形成的星系和AGN主导的系统位于PAH诊断图的不同区域。这表明，不仅PAH分子的大小和电荷不同，而且是辐射场激发它们的性质和硬度。我们发现暂定证据表明，AGN主导系统中的PAH比与较大的PAH分子（NC> 300-400）和中性物种的发射一致。通过从总数中减去中央源的频谱，我们比较了一小部分AGN样品的中央与扩展区域中的PAH发射。与AGN主导系统的中央区域的发现相反，可以解释在1型和2型Seyfert星系的扩展区域中测量的PAH比率，假设分子的分子尺寸分布相似，并且分子离子分数相似，而分子的电离级分与在星形形成星系的中央区域（100 <nc <300 <300 <300）中所见。
Polycyclic Aromatic Hydrocarbons (PAHs) are carbon-based molecules resulting from the union of aromatic rings and related species, which are likely responsible for strong infrared emission features (3.3, 6.2, 7.7, 8.6, 11.3 and 12.7 microns). In this work, using a sample of 50 Seyfert galaxies (DL<100 Mpc) we compare the circumnuclear (inner kpc) PAH emission of AGN to that of a control sample of star-forming galaxies (22 luminous infrared galaxies and 30 HII galaxies), and investigate the differences between central and extended PAH emission. Using Spitzer/InfraRed Spectrograph spectral data of Seyfert and star-forming galaxies and newly developed PAH diagnostic model grids, derived from theoretical spectra, we compare the predicted and observed PAH ratios. We find that star-forming galaxies and AGN-dominated systems are located in different regions of the PAH diagnostic diagrams. This suggests that not only are the size and charge of the PAH molecules different, but also the nature and hardness of the radiation field that excite them. We find tentative evidence that PAH ratios in AGN-dominated systems are consistent with emission from larger PAH molecules (Nc>300-400) as well as neutral species. By subtracting the spectrum of the central source from the total, we compare the PAH emission in the central vs extended region of a small sample of AGN. In contrast to the findings for the central regions of AGN-dominated systems, the PAH ratios measured in the extended regions of both type 1 and type 2 Seyfert galaxies can be explained assuming similar PAH molecular size distribution and ionized fractions of molecules to those seen in central regions of star-forming galaxies (100<Nc<300).
