发表机构
Purdue University（普渡大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过延迟离轴喷流模型解释AT2018hyz的晚期射电增亮，并利用天空投影预测打破观测角度与延迟时间的简并，为未来VLBI观测提供指导。
AI 中文摘要
潮汐瓦解事件（TDE）AT2018hyz最初通过光学手段被发现，并在972天后首次在射电波段被探测到。对该事件的持续监测揭示了其晚期（1370-2160天）的射电增亮现象。这一射电增亮的来源被认为与离轴喷流或延迟的温和相对论性外流产生的余辉有关。在本工作中，我们探索了延迟离轴喷流解释所观测到的射电增亮所需的条件。我们发现，不同的延迟时间（t_delay）和观测者角度（theta_obs）的联合效应可以产生如AT2018hyz所观测到的射电余辉。观测者相对于喷流核心的离轴角度越大，光学瓦解与喷流发射之间推断的延迟时间就越短。这导致了不同theta_obs和tdelay之间的简并性。我们估算了这些不同组合下喷流的天空投影，以打破这种简并性。天空图像的分布范围从30度离轴观测者的0.6毫角秒到垂直于喷流核心观测者的0.3毫角秒。未来的VLBI观测应能分辨这些结构。因此，对AT2018hyz（以及其他喷流TDE）的光变曲线和天空图像的联合观测，可用于缩小观测者角度和底层喷流发射延迟的不确定性。
英文摘要
Initially discovered optically, Tidal Disruption Event (TDE) AT2018hyz was first detected in radio 972 days later. The continued monitoring of the event revealed a late-time (1370-2160 days) radio brightening. The source for this radio brightening has been associated with an afterglow originating from an off-axis jet or a delayed mildly relativistic outflow. In this work, we explored the conditions required for a delayed off-axis jet to explain the observed radio brightening. We find that the combined effect of different delay times (t_delay) and observer angles (theta_obs) can produce radio afterglow, as observed for AT2018hyz. The further off-axis from the jet core an observer is, the shorter is the delay inferred between the optical disruption and launching of the jet. This presents a degeneracy between different theta_obs and tdelay. We estimate the sky projection of the jet for these different combinations to break this degeneracy. The spread in sky images ranges from 0.6 mas for a 30 deg off-axis observer to 0.3 mas for an observer perpendicular to the jet core. Future VLBI observations should be able resolve these structures. Thus a combined observation of the light curve and sky images for AT2018hyz (and other jetted TDEs) can be used to narrow down the observer angle and any delay in launching of the underlying jet.
Comments10 Pages of manuscript without references, with 6 figures including one schematic diagram
