Parkes observations for project P1328 semester 2025APRS_13

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）是一类奇特的微毫秒级持续时长的瞬态信号，现已被证实具有河外起源。自其被发现以来，该源群便呈现出鲜明的二分特性：部分FRB表现出重复爆发特征，而其余则未观测到重复爆发现象。以FRB 20180301A为代表的重复暴FRB，凭借其重复爆发的特性，为研究其爆发周围环境提供了独一无二的观测窗口，可用于约束潜在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）符号的翻转，这一现象表明其周围磁场发生反转，且在低频段线性偏振占比显著降低（即去偏振效应）。过往针对该源的帕克斯/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低频宽带（Ultra-wideband Low, UWL）接收机非常适合用于探究该源的宽带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，以建模磁场演化过程、通过去偏振效应研究其爆发周围介质，并约束DM与RM之间的相关性。