Parkes observations for project P1328 semester 2025APRS_14

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，该类天体的观测种群呈现出清晰的二分特性：部分FRB表现出重复爆发行为，而另一类则未观测到重复爆发现象。以FRB 20180301A为代表的重复暴，凭借其重复爆发的特性，为研究暴周环境提供了无与伦比的观测窗口，可用于约束FRB的前身天体模型并检验其核心辐射机制。此外，FRB 20180301A已被观测到具备独特的偏振特性，例如旋转量（Rotation Measure, RM）符号的切换现象，这指示其磁场发生反转，且在低频段呈现出线偏振度显著降低的退偏振效应。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（UWL）接收机，非常适合用于探究该源的宽频光谱时域与偏振测量特性。本研究提议利用该超宽带低频接收机对FRB 20180301A开展定期监测，以建模其磁场演化过程、通过退偏振效应研究其暴周介质，并约束色散量与旋转量之间的相关性。