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arXiv 2202.04851astro-ph.GA
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Seyfert星系的SkyMapper颜色和外观变化的AGN-II。新发现的外观变化型AGN

SkyMapper colours of Seyfert galaxies and Changing-look AGN-II. Newly discovered Changing-look AGN

Wei Jeat Hon, Christian Wolf, Christopher Onken, Rachel Webster, Katie Auchettl

摘要:

变貌活动星系核(CLAGN)是一种活动星系核,随着其宽发射线的出现或消失而改变类型,这通常伴随着其蓝色无特征连续谱中强通量的变化。我们通过从光谱6dF星系巡天中选择2型活动星系核来寻找开启CLAGN,其测光,十多年后由SkyMapper南方巡天观察到,与1型活动星系核一致。从235个已知的2型活动星系核的随机样本开始,我们选择了18个候选者,并确认13个活动星系核已转变为1型谱;一个不完整的样本的观测揭示了9个进一步的开启CLAGN。虽然我们的搜索并不是为了可靠地发现关闭CLAGN,但我们也发现了四个这样的案例。这一结果表明,在约15年内,开启CLAGN率为12%,并意味着在此期间总CLAGN率为约25%。最后,我们提出了活动星系核的观察是典型的CLAGN现象,包括J1109146 -一个CLAGN,没有出现在6dFGS活动星系核; J1406507 -第二次报告Changinglook NLS 1;和J1340153 -一个CLAGN的变化时间尺度为三个月。

英文摘要:

Changing-look Active Galactic Nuclei (CLAGN) are AGN that change type as their broad emission lines appear or disappear, which is usually accompanied by strong flux changes inn their blue featureless continuum. We search for Turn-On CLAGN by selecting type-2 AGN from the spectroscopic 6dF Galaxy Survey, whose photometry, as observed over a decade later by the SkyMapper Southern Survey, is consistent with type-1 AGN. Starting from a random sample of 235 known type-2 AGN we select 18 candidates and confirm 13 AGN to have changed into type-1 spectra; observations of an incomplete sample reveal nine further Turn-On CLAGN. While our search was not intended to reliably discover Turn-Off CLAGN, we discover four such cases as well. This result suggests a Turn-On CLAGN rate of 12% over ~15 years and imply a total CLAGN rate of ~25% over this period. Finally, we present observations of AGN that are atypical for the CLAGN phenomenology, including J1109146 - a CLAGN that did not appear as an AGN in 6dFGS; J1406507 - the second reported Changinglook NLS1; and J1340153 - a CLAGN with a change timescale of three months.

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