标题： 近邻星系核区与非核区的中红外光谱诊断 显示英文标题

标题： Mid-Infrared Spectral Diagnostics of Nuclear and Extra-Nuclear Regions in Nearby Galaxies

摘要： 红外诊断展示了斯皮策红外近邻星系巡天（SINGS）样本中大部分以及来自红外空间天文台和斯皮策太空望远镜的存档数据的结果。我们的主要结论是，这些中红外诊断有效地限制了目标的主要能源。高电离线指数与PAH强度的结合可以作为活动星系核（AGN）和恒星形成核区的有效区分指标，这证实了通过ISO光谱学在爆发星系和超亮红外星系方面的进展。斯皮策望远镜的灵敏度使我们能够探测到星系盘内更微弱的核区和恒星形成区域。我们发现，恒星形成核区和星系外区域都明显不同于由塞弗特或LINER活动驱动的核区。实际上，我们在四个诊断图中识别出包含>90%塞弗特/LINER核区或>90%HII区/HII核区的区域。我们还发现，与爆发核区相比，星系外区域通常与AGN分离得更远，特别是在低金属丰度的星系外环境中。此外，与传统利用相对较弱的高电离线来区分AGN和恒星形成源的方法不同，我们表明，像[SiII] 34.82微米这样的X射线主导区域的强低电离冷却线也可以用作优秀的区分指标。最后，这个样本中的典型目标显示出相对适中的星际电子密度（~400 cm^{-3}）和遮蔽程度（前景屏的A_V ~ 1.0 mag），这与发射区域中没有大量密集且高度遮蔽的气体和尘埃团块一致。 [简化版] 显示英文摘要

摘要： Mid-infrared diagnostics are presented for a large portion of the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample plus archival data from the Infrared Space Observatory and the Spitzer Space Telescope. Our main result is that these mid-infrared diagnostics effectively constrain a target's dominant power source. The combination of a high ionization line index and PAH strength serves as an efficient discriminant between AGN and star-forming nuclei, confirming progress made with ISO spectroscopy on starbursting and ultraluminous infrared galaxies. The sensitivity of Spitzer allows us to probe fainter nuclei and star-forming regions within galaxy disks. We find that both star-forming nuclei and extranuclear regions stand apart from nuclei that are powered by Seyfert or LINER activity. In fact, we identify areas within four diagnostic diagrams containing >90% Seyfert/LINER nuclei or >90% HII regions/HII nuclei. We also find that, compared to starbursting nuclei, extranuclear regions typically separate even further from AGN, especially for low-metallicity extranuclear environments. In addition, instead of the traditional mid-infrared approach to differentiating between AGN and star-forming sources that utilizes relatively weak high-ionization lines, we show that strong low-ionization cooling lines of X-ray dominated regions like [SiII] 34.82 micron can alternatively be used as excellent discrimants. Finally, the typical target in this sample shows relatively modest interstellar electron density (~400 cm^{-3}) and obscuration (A_V ~ 1.0 mag for a foreground screen), consistent with a lack of dense clumps of highly obscured gas and dust residing in the emitting regions. [Abridged]