Parkes observations for project P1328 semester 2024APRS_19

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）是一类持续时间仅为微毫秒级的特殊暂现源，其起源已被证实为河外天体。自发现以来，FRB群体呈现出明显的二分性：部分FRB表现出重复爆发特性，而另一部分则未观测到重复现象。重复型FRB（如FRB 20180301A）因其重复爆发的特性，为研究其爆发周边环境提供了独一无二的窗口，这有助于限制可能的前身星模型，并检验其内在的辐射机制。此外，FRB 20180301A还表现出有趣的偏振特性，例如旋转量（Rotation Measure, RM）符号的切换，这表明磁场发生了反转；同时，其线偏振分数在低频段显著降低（即去偏振现象）。此前对Parkes/Murriyang望远镜观测到的该源的后续研究还揭示了其色散量（Dispersion Measure, DM）的时间演化特性，以及DM与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）接收器非常适合探索该源的宽带光谱时间特性和偏振行为。我们建议利用UWL对FRB 20180301A进行定期监测，以建立磁场演化模型，通过去偏振行为研究其爆发周边介质，并进一步限制DM与RM之间的相关性。