AI 中文总结
本研究通过VLA观测发现，变貌AGN Mrk 590的射电增亮由弓激波驱动，其射电变异性与高能波段的吸积变事件无关联，揭示了变貌AGN行为机制的多样性。
AI 中文摘要
Mrk 590 是一个变貌活动星系核（CLAGN），在数十年间从赛弗特1型星系缓慢衰减至近静息态，于2017年重新活跃。光学、紫外、X射线波段的监测已揭示出吸积驱动的变光特征，但射电源对驱动其衰减与重新活跃的变貌事件的响应仍未知。我们呈现了2015至2017年四个历元对 Mrk 590 的多频（1-17 GHz）A阵卡尔·G·詹斯基甚大阵（VLA）观测数据，该射电源以一个暗弱的致密成分为主，无明显延展结构。我们识别出该时段内射电谱在振幅与形态上均存在变化，并采用贝叶斯推断建模程序约束射电变异性的驱动机制。该程序支持射电变异性由射电喷流与星际介质相互作用产生的弓激波驱动，后者导致后续历元的射电增亮。这表明我们观测到的射电变异性与导致该活动星系核在高能波段重新增亮的吸积变事件无关联。尽管在其他变貌活动星系核中已观测到射电与吸积驱动辐射间的变光相关性，但 Mrk 590 中缺乏此类相关性，显示出变貌活动星系核群体及其行为驱动机制的多样性。
英文摘要
Mrk 590 is a changing-look AGN (CLAGN) that slowly faded from a Seyfert Type 1 to near quiescence over a few decades before re-igniting in 2017. Monitoring in the optical/UV/X-ray wavebands has revealed accretion-driven variability signatures, but the response of the radio source to the changing-look events that drove its fading and re-ignition is unknown. We present multi-frequency (1-17~GHz), A-configuration, Karl G. Jansky Very Large Array (VLA) observations of Mrk 590 over four epochs from 2015 to 2017. The radio source is dominated by a faint, compact component, absent of any notable extended structures. We identify a variable radio spectrum over this period, both in amplitude and in shape, and implement a Bayesian inference modeling routine to constrain the mechanism driving the radio variability. Our routine favors radio variability powered by a bow shock produced through an interaction of a radio jet with the interstellar medium, which drives the radio brightening in later epochs. This demonstrates that the radio variability we observed is not correlated with the variable accretion event that led to the re-brightening of the AGN at higher energy wavebands. While correlated variability between the radio and accretion-driven emission has been observed in other CLAGN, the lack of correlated variability in Mrk 590 shows the diversity of changing-look AGN populations and the mechanisms driving their behavior.
Comments11 pages, 3 figures, 3 tables
