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arXiv 2201.07250astro-ph.GA
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通过空间分辨光谱学对活动星系核进行更全面的光学普查

Towards a More Complete Optical Census of Active Galactic Nuclei, Via Spatially-Resolved Spectroscopy

Julia M. Comerford, James Negus, R. Scott Barrows, Dominika Wylezalek, Jenny E. Greene, Francisco Müller-Sánchez, Rebecca Nevin

摘要:

虽然发射线通量比诊断是最常见的技术,用于确定活动星系核(AGN)的光学光谱,应用这种方法的星系的单纤维光谱可以忽略整个亚群的AGN。在这里,我们使用空间分辨光谱从映射附近的Galaxies在Apache点天文台(MANGA)调查,以构建一个样本的10个星系的鲍德温-飞利浦-Terlevich线通量比诊断分类每个星系的中央$3^{\prime\prime}$光谱LINER或恒星形成,而$>10\%$的spaxels在星系的MANGA足迹被归类为塞弗特。我们获得钱德拉观测这10个星系的离核塞弗特地区,以确定是否活动星系核实际上存在于其中。我们的主要结果是,7-10(取决于严格的标准)的星系主机一个或多个X射线活动星系核,即使没有一个被归类为活动星系核的基础上,他们的单纤维光学光谱。我们发现这些活动星系核在单纤维光谱中没有被识别,因为它们是伴星系核中的活动星系核、低光度活动星系核、尘埃遮蔽活动星系核和/或闪烁活动星系核。总之,我们发现,离核活动星系核的签名可能会增加已知活动星系核的数量比传统的单核纤维光谱识别的两倍。我们的研究结果表明,空间分辨光谱可以用来揭示一个更完整的普查AGN传统上错过了单纤维光谱。

英文摘要:

While emission-line flux ratio diagnostics are the most common technique for identifying active galactic nuclei (AGNs) in optical spectra, applying this approach to single fiber spectra of galaxies can omit entire subpopulations of AGNs. Here, we use spatially resolved spectroscopy from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey to construct a sample of 10 galaxies where Baldwin-Philips-Terlevich line flux ratio diagnostics classify each galaxy's central $3^{\prime\prime}$ spectrum as LINER or star forming, while $>10\%$ of the spaxels in the galaxy's MaNGA footprint are classified as Seyfert. We obtain Chandra observations of these 10 galaxies with off-nuclear Seyfert regions to determine whether AGNs are actually present in them. Our main result is that 7-10 (depending on strictness of criteria) of the galaxies host one or more X-ray AGNs, even though none of them were classified as AGNs based on their single-fiber optical spectra. We find that these AGNs were not identified in the single-fiber spectra because they are AGNs in the nuclei of companion galaxies, low luminosity AGNs, dust obscured AGNs, and/or flickering AGNs. In summary, we find that off-nuclear AGN signatures may increase the number of known AGNs by a factor of two over what conventional single nuclear fiber spectra identify. Our results show that spatially resolved spectroscopy can be leveraged to reveal a more complete census of AGNs that are traditionally missed by single fiber spectra.

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