AT 2022csn：II型活动星系核中一颗测光特性特殊的光学/紫外潮汐瓦解事件
AT 2022csn: A Photometrically Peculiar Optical/UV Tidal Disruption Event in a Type II AGN
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中文总结 AI 辅助
本研究报道了II型AGN中一颗测光特殊的光学/紫外TDE AT 2022csn，其为遥远且明亮的TDE，或属于低温高半径TDE新子群，提出TDE与AGN吸积盘相互作用等场景解释其特性。
中文摘要 AI 辅助
光学/紫外潮汐瓦解事件（TDE）的辐射机制及其宿主星系的偏好性仍未被完全理解。我们呈现了对TDE AT 2022csn的观测结果，它是迄今观测到的最遥远（光度距离d_L≈726 Mpc）、最明亮（峰值光度L_peak=2.487^(+0.073)_(-0.067)×10^44 erg/s）的光学/紫外TDE之一。尽管它是光谱上正常的H+He型TDE，却表现出一些测光特殊性：在g波段呈现出显著的双峰值光变曲线（峰值间隔为18.30±2.84天），且处于光学/紫外TDE群体的低温、大半径端。AT 2022csn的宿主星系显示出过去约1 Gyr内存在显著恒星形成爆发的证据，这与其他光学/紫外TDE的情况一致；同时其窄发射线将其置于BPT图的II型活动星系核（AGN）区域。TDE与已存在的AGN吸积盘之间的相互作用或许能解释这些特殊的测光特性，但令人困惑的是，根据AGn统一模型，II型AGN中超大质量黑洞周围的中心区域是被遮蔽的，TDE却能在这类天体中被观测到。我们提出了一些协调这一矛盾的可能场景。AT 2022csn与具有相似特性的AT 2019ahk可能属于II型AGN发射特征星系中一类新的低温、高半径TDE子群。
英文摘要
The emission mechanism and host galaxy preference of optical/UV tidal disruption events (TDEs) are still not entirely understood. We present observations of the TDE AT 2022csn, which is one of the most distant (d_L~726 Mpc) and luminous (L_peak=2.487^(+0.073)_(-0.067)*10^(44) erg/s) optical/UV TDEs observed to date. Although it is a spectroscopically normal H+He TDE, it shows some photometric peculiarities, exhibiting a pronounced double-peaked light curve (with peaks separated by 18.30 pm 2.84 days in the g-band), and lying in the low-temperature and large-radius end of the optical/UV TDE population. The host galaxy of AT 2022csn shows evidence for a significant starburst within the last ~Gyr consistent with other optical/UV TDEs, but also narrow emission lines that place it within the Type II AGN region of the BPT diagram. Interaction between the TDE and a pre-existing AGN accretion disk might explain the peculiar photometric properties. However, it is puzzling that a TDE would be visible in a Type II AGN, where according to the AGN unification picture the central region around the supermassive black hole is obscured. We suggest a few scenarios to reconcile this. AT 2022csn together with AT 2019ahk, which shows similar properties, may belong to a new subset of low-temperature, high-radius TDEs in galaxies with Type II AGN emission features.
