论文标题
神秘性变化外观的无线电，光学，紫外线和X射线视图从其前到发光状态，〜1927+654
A radio, optical, UV and X-ray view of the enigmatic changing look Active Galactic Nucleus 1ES~1927+654 from its pre- to post-flare states
论文作者
论文摘要
附近的II型AGN 1ES1927+654从2017年12月开始经历了一次暴力更换（CL）活动，在此期间，光学和紫外线通量在几个月内增加了四个大小，并且在光学/UV中新出现了较大的发射线。到2018年7月，X射线冠状排放已经完全消失，直到几个月后才出现。在这项工作中，我们报告了无线电，光学，紫外线和X射线从前拍照状态到2021年中期的演变，并提供了很长的基线阵列（VLBA），欧洲VLBI网络的新和档案数据，这是非常大的VLBI网络，非常大的阵列（VLA），Telescopio nazionale nazionale gahileo（tng），geil can telescopio can arhiascopio（gtc）天文台和XMM-Newton。我们工作的主要结果是：（1）源以光学，紫外线和X射线返回其前CL状态；磁盘 - 核心关系已经像在前CL状态一样重新建立，$α_ {\ rm ox} \ sim 1.02 $。光谱由狭窄的发射线主导。 （2）与潮汐破坏事件所预测的相比，紫外线曲线遵循$ \ propto t^{ - 0.91 \ pm 0.04} $的浅坡。我们猜想磁通量倒转事件是该神秘事件的可能原因。 （3）我们在Pre-CL（2014），CL（2018）和CL（2021）在空间尺度上追踪的紧凑型无线电发射在2018年不断变化的外观事件中处于最低水平，几乎同时发生的是最低水平，几乎是$ 2-10 $ KEV $ kev发射。紧凑型源的无线电与X射线比率$ l _ {\ rm Radio}/l _ {\ rm X-ray} \ sim 10^{ - 5.5} $，遵循Gudel-Benz关系，通常在冠状星星中发现，并且是几个AGN。 （4）我们没有在$ \ sim 5-10 $ PC的空间尺度上检测到任何新生喷气机的存在。
The nearby type-II AGN 1ES1927+654 went through a violent changing-look (CL) event beginning December 2017 during which the optical and UV fluxes increased by four magnitudes over a few months, and broad emission lines newly appeared in the optical/UV. By July 2018 the X-ray coronal emission had completely vanished, only to reappear a few months later. In this work we report the evolution of the radio, optical, UV and X-rays from the pre-flare state through mid-2021 with new and archival data from the Very Long Baseline Array (VLBA), the European VLBI Network, the Very Large Array (VLA), the Telescopio Nazionale Galileo (TNG), Gran Telescopio Canarias (GTC), The Neil Gehrels Swift observatory and XMM-Newton. The main results from our work are: (1) The source has returned to its pre-CL state in optical, UV, and X-ray; the disk-corona relation has been re-established as has been in the pre-CL state, with an $α_{\rm OX}\sim 1.02$. The optical spectra are dominated by narrow emission lines. (2) The UV light curve follows a shallower slope of $\propto t^{-0.91\pm 0.04}$ compared to that predicted by a tidal disruption event. We conjecture that a magnetic flux inversion event is the possible cause for this enigmatic event. (3) The compact radio emission which we tracked in the pre-CL (2014), during CL (2018) and post-CL(2021) at spatial scales $<1$ pc was at its lowest level during the changing look event in 2018, nearly contemporaneous with a low $2-10$ keV emission. The radio to X-ray ratio of the compact source $L_{\rm Radio}/L_{\rm X-ray}\sim 10^{-5.5}$, follows the Gudel-Benz relation, typically found in coronally active stars, and several AGN. (4) We do not detect any presence of nascent jets at the spatial scales of $\sim 5-10$ pc.
