Parkes observations for project P1338 semester 2024OCTS_35

Fast radio bursts (FRBs) are millisecond-duration radio bursts of extragalactic origin. Since the discovery of the first FRB in the archival Parkes/Murriyang multibeam data, a broad dichotomy in population has emerged. Some FRBs have been seen to be repeating, while others are not, despite a significant amount of follow-up using different radio telescopes. The repeating FRB 20240114A was recently discovered by CHIME/FRB, which has been seen to have an exceptionally high burst activity. Such extreme burst activity has not been seen in any other source. The repeating FRBs, such as FRB 20240114A, 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. The previous Parkes/Murriyang source follow-up has also revealed intriguing spectro-polarimetric properties, such as frequency-dependent evolution of burst central frequency or chromaticity, a possible activity window, significantly large circular polarisation (CP), and frequency-dependent CP. These properties hold the key towards understanding the circumburst environment of the FRBs, and test possible progenitor models. A large bandwidth instrument with reliable polarimetry has been critical in uncovering these properties. The ultra-wideband low (UWL) receiver on Parkes/Murriyang is ideally suited to explore the source's wideband spectro-temporal and polarimetric behaviour. We propose a campaign to regularly follow up FRB 20240114A to ascertain its long-term evolution of spectro-temporal properties.

快速射电暴（Fast radio bursts，FRBs）是起源于河外星系、持续时长仅为毫秒级的射电暴。自档案中的帕克斯/穆里扬多波束观测数据里发现首例快速射电暴以来，该类暴源的种群已呈现出显著的二分性：尽管学界已利用多台不同射电望远镜开展了大量后续观测，但部分快速射电暴被证实会重复爆发，而另一部分则仅单次爆发。重复暴源FRB 20240114A近期由加拿大氢强度测绘实验-快速射电暴（CHIME/FRB）项目发现，该暴源展现出异常高的爆发活动频次，此类极端的爆发活动在其他任何暴源中均未被观测到。诸如FRB 20240114A这类重复爆发的快速射电暴，凭借其重复爆发的特性，为研究其暴周环境提供了无可比拟的窗口，可用于约束各类潜在的前身天体模型，并检验其核心辐射机制。此前针对帕克斯/穆里扬观测到的暴源开展的后续研究，还揭示了诸多引人关注的光谱偏振特性：例如暴源中心频率随频率的演化（或称色散特性）、可能存在的爆发活动窗口、极高的圆偏振度（circular polarisation，CP），以及圆偏振度随频率的变化关系。这些特性是破解快速射电暴暴周环境、验证各类潜在前身天体模型的关键所在。具备可靠偏振测量能力的大带宽观测设备，是揭示上述特性的关键工具。帕克斯/穆里扬望远镜搭载的超宽带低（ultra-wideband low，UWL）接收机，恰好能够完美适配该暴源的宽频光谱时域与偏振特性研究。我们提议开展一项针对FRB 20240114A的常态化后续观测计划，以明确其光谱时域特性的长期演化规律。