标题： 近邻星系的中红外光谱诊断 显示英文标题

标题： Mid-Infrared Spectral Diagnostics of Nearby Galaxies

摘要： 斯皮策太空望远镜正在推动高红移天文学的新领域。 在离家更近的地方，斯皮策同样极大地影响了我们对星系形成与演化的理解。 在这篇贡献中，我们提出了基于斯皮策红外邻近星系巡天（SINGS）数据的中红外诊断方法。 我们的主要结果表明，这些中红外诊断有效地限制了一个目标的主要能源。 高电离线指数和PAH强度的结合可以作为AGN和恒星形成核之间的有效判别标准，这证实了通过ISO光谱学在爆发星系和超亮红外星系方面取得的进展。 斯皮策的灵敏度使我们能够探测星系盘内更微弱的核心和恒星形成区域。 我们发现，恒星形成核和星系外区域明显不同于由Seyfert或LINER活动驱动的核心。 事实上，我们在三个诊断图中识别出包含>90% Seyfert/LINER核心或>90% HII区/HII核的区域。 我们还发现，与爆发核相比，星系外区域通常与AGN分离得更远，尤其是在低金属丰度的星系外环境中。 此外，我们展示了一种替代传统中红外方法的方法，该方法利用相对较弱的高电离线来区分AGN和恒星形成源，即使用像[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作为优秀的判别标准。 显示英文摘要

摘要： The Spitzer Space Telescope is pushing into new frontiers in high redshift astronomy. Closer to home, Spitzer is making an equally large impact on our understanding of galaxy formation and evolution. In this contribution we present mid-infrared diagnostics based largely on data from the Spitzer Infrared Nearby Galaxies Survey (SINGS). 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 three 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.