Parkes observations for project P1328 semester 2024OCTS_09

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的瞬变源，现已确认其起源于河外天体。自被发现以来，其观测样本群体呈现出显著的二分性：部分FRB表现出重复爆发特性，另一部分则尚未观测到重复爆发行为。以FRB 20180301A为代表的重复快速射电暴，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，可用于约束其可能的前身天体模型并检验核心辐射机制。此外，FRB 20180301A已被观测到具有独特的偏振特性：例如旋转量（Rotation Measure, RM）符号发生反转，这指示其磁场出现反转；同时在低频段观测到线偏振度显著降低（即去偏振现象）。此前针对该源的帕克斯/穆里扬（Parkes/Murriyang）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存在相关性的初步观测证据。帕克斯/穆里扬望远镜搭载的超宽带低（Ultra-wideband Low, UWL）接收机，非常适合用于探究该源的宽带频谱-时域与偏振观测特性。本研究拟利用该接收机对FRB 20180301A开展常态化监测，以建模其磁场演化过程、通过去偏振特性研究其暴周介质，并约束色散量与旋转量之间的相关性。