Variability Selected Active Galactic Nuclei from ASAS-SN Survey: Constraining the Low Luminosity AGN Population
Variability Selected Active Galactic Nuclei from ASAS-SN Survey: Constraining the Low Luminosity AGN Population
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DOI：
10.3847/1538-4357/ac6423
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发表时间：
2022-03
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通讯作者：
H. Yuk;X. Dai;T. Jayasinghe;H. Fu;Hora D. Mishra;C. Kochanek;B. Shappee;K. Oklahoma;The Ohio State University;U. Iowa;University of Hawai'i
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作者：
H. Yuk;X. Dai;T. Jayasinghe;H. Fu;Hora D. Mishra;C. Kochanek;B. Shappee;K. Oklahoma;The Ohio State University;U. Iowa;University of Hawai'i
低光度活动星系核（LLAGN）探测低爱丁顿区域的吸积物理可以提供有关星系演化的额外线索。 AGN 变异性无处不在，因此为寻找 AGN 提供了可靠的工具。我们分析了 g < 14 mag 的 1218 个星系的全天自动巡天超新星光变曲线和斯隆数字巡天光谱，以寻找活动星系核。我们发现 37 个既可变又具有类似 AGN 结构函数的物体，约占样本的 3%。所选 AGN 的大部分变异性是 LLAGN，爱丁顿比率范围为 10−4 到 10−2。因此，我们估计 LLAGN 在星系群中的比例为 2%，爱丁顿比率中位数为 2 × 10−3。结合 BPT 线比 AGN 诊断和宽线 AGN，高达约 60% 的 AGN 候选者通过光谱得到确认。 BPT 诊断还将 10%–30% 的候选星系分类为恒星形成星系，而不是活动星系核。
Low luminosity active galactic nuclei (LLAGN) probe accretion physics in the low Eddington regime can provide additional clues about galaxy evolution. AGN variability is ubiquitous and thus provides a reliable tool for finding AGN. We analyze the All-Sky Automated Survey for SuperNovae light curves of 1218 galaxies with g < 14 mag and Sloan Digital Sky Survey spectra in search of AGN. We find 37 objects that are both variable and have AGN-like structure functions, which is about 3% of the sample. The majority of the variability selected AGN are LLAGN with Eddington ratios ranging from 10−4 to 10−2. We thus estimate the fraction of LLAGN in the population of galaxies as 2% down to a median Eddington ratio of 2 × 10−3. Combining the BPT line ratio AGN diagnostics and the broad-line AGN, up to ∼60% of the AGN candidates are confirmed spectroscopically. The BPT diagnostics also classified 10%–30% of the candidates as star-forming galaxies rather than AGN.