Parkes observations for project P1328 semester 2025APRS_01

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源，现已确认其起源于河外天体。自被发现以来，FRB群体便呈现出鲜明的二分特性：部分FRB表现出重复爆发行为，另一部分则始终未观测到重复爆发现象。以FRB 20180301A为代表的重复爆发FRB，凭借其重复爆发的固有特性，为研究其暴周环境提供了独一无二的观测窗口，可用于约束其前身天体模型并检验核心辐射机制。此外，FRB 20180301A展现出极具研究价值的偏振特性：例如其旋转量（Rotation Measure, RM）的符号发生反转，这一现象指示其周围磁场出现反转；同时在低频段观测到线偏振度显著降低，即退偏振效应。此前基于帕克斯（Parkes）/穆里扬（Murriyang）望远镜开展的源后续观测，还揭示了该源的色散量（Dispersion Measure, DM）存在时间演化特征，以及DM与RM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，非常适合用于探究该源的宽频谱时行为与偏振测量特性。本研究提议利用UWL接收机对FRB 20180301A开展定期监测，以建模其周围磁场的演化过程、通过退偏振效应研究暴周介质，并约束DM与RM之间的相关性。