Parkes observations for project P1328 semester 2024APRS_08

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暂现源，已被证实具有河外起源。自发现以来，FRB群体呈现出二分性特征：部分FRB表现出重复爆发行为，而另一部分则未观测到重复现象。重复型FRB（如FRB 20180301A）因其重复爆发特性，为研究其爆发周环境提供了独特窗口，可用于约束可能的前身星模型并检验潜在辐射机制。此外，FRB 20180301A具有有趣的偏振特性，例如旋转量（Rotation Measure，RM）符号发生反转，这表明磁场存在倒转；同时，其线偏振分数在低频段显著降低（去偏振现象）。此前利用Parkes/Murriyang望远镜对该源的后续观测还揭示了其色散量（Dispersion Measure，DM）的时间演化特征，以及DM与旋转量（RM）之间存在相关性的初步证据。Parkes/Murriyang望远镜搭载的超宽带低频（Ultra-Wideband Low，UWL）接收机非常适合研究该源的宽带频谱-时间特性及偏振行为。我们建议利用UWL对FRB 20180301A进行定期监测，以建模其磁场演化过程、通过去偏振行为研究爆发周介质，并进一步约束DM与RM之间的相关性。