Parkes observations for project P1328 semester 2025APRS_11

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, FRB）是一类特殊的微毫秒级持续时间瞬变天体，现已证实其起源于河外星系。自被发现以来，该类天体的群体便呈现出明确的二分特性：部分FRB表现出重复爆发行为，而另一类则未被观测到重复爆发。以FRB 20180301A为代表的重复型快速射电暴，凭借其重复爆发的特质，为探究其暴周环境提供了无可比拟的观测窗口，可用于约束潜在的前身天体模型并检验核心辐射机制。此外，FRB 20180301A已被观测到存在多项有趣的偏振特性：例如旋转量（Rotation Measure, RM）的符号发生反转，这意味着其周围磁场出现反转；同时在低频段观测到线偏振占比显著下降，即去偏振效应。此前针对该源的帕克斯/穆里扬望远镜后续观测还揭示了其色散量（Dispersion Measure, DM）的时间演化特征，以及色散量与旋转量之间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，非常适合用于研究该源的宽频光谱时域与偏振行为。本研究提议利用UWL接收机对FRB 20180301A开展定期监测，以建模其磁场演化过程、通过去偏振效应分析其暴周介质，并约束色散量与旋转量之间的相关性。