Parkes observations for project P1328 semester 2024APRS_12

Fast radio bursts are peculiar micro-millisecond duration transients, which have been seen to be extragalactic in origin. Since their discovery, a dichotomy has emerged in their population. Some FRBs have been seen to be repeating, while others have not been seen to be repeating. The repeating FRBs, such as FRB 20180301A, provide an unparalleled window into their circumburst environment due to their repeating nature, which can be used to constrain possible progenitor models and test underlying emission mechanisms. Additionally, FRB 20180301A has been seen to have interesting polarisation properties, such as a switch in the sign of RM, indicating a reversal in the magnetic field and a marked reduction in the linear polarisation fraction towards lower frequencies (depolarisation). The previous Parkes/Murriyang source follow-up has also revealed a temporal evolution in the dispersion measure (DM) of the source and tentative evidence for correlation in the DM and rotation measure (RM). The ultra-wideband low (UWL) receiver on Parkes/Murriyang is ideally suited to explore the wideband spectro-temporal and polarimetric behaviour of the source. We propose regular monitoring of FRB 20180301A using UWL to model the magnetic field evolution, study its circumburst media using depolarisation behaviour, and constrain any correlation of DM and RM.

快速射电暴（Fast Radio Bursts, FRBs）是一类特殊的微毫秒级持续时间暂现源，现已被证实起源于河外空间。自发现以来，其观测样本呈现出明确的二分特性：部分快速射电暴表现出重复爆发行为，而另一部分则未观测到重复爆发。重复爆发快速射电暴（如FRB 20180301A）凭借其重复爆发的特性，为研究其暴周环境提供了独一无二的观测窗口，可用于约束可能的前身星模型并检验核心辐射机制。此外，FRB 20180301A展现出极具科研价值的偏振特性：例如旋转测量（Rotation Measure, RM）符号发生反转，这表明其周围磁场发生逆转；同时在低频段，线偏振度出现显著降低（即去偏振现象）。此前针对帕克斯/穆里扬望远镜（Parkes/Murriyang）观测源的后续研究，还揭示了该源的色散测量（Dispersion Measure, DM）随时间演化的特征，以及DM与RM存在相关性的初步证据。帕克斯/穆里扬望远镜搭载的超宽带低频（Ultra-Wideband Low, UWL）接收机，非常适合开展该源的宽带谱时域特性与偏振行为研究。本研究提议利用UWL接收机对FRB 20180301A开展常态化监测，以建模其磁场演化过程、通过去偏振现象研究其暴周介质，并约束DM与RM的相关性特征。