Parkes observations for project P1136 semester 2021OCTS_01

Fast radio bursts (FRBs) continue to raise more questions than they answer. Of an order of a thousand discovered FRBs, only 20 of them are known to repeat, and their spectro-temporal properties hint at differences with apparently non-repeating bursts. The repeating FRB sources show varying degrees of activity, with two of them emitting repetitions in a periodic cycle. Here we propose to study repetitions in a sample of five repeating FRB sources, ASKAP-discovered FRB20171019A and FRB20190711A, Parkes-discovered FRB20180301A and CHIME-discovered FRB20201124A and FRB20190117A. We request Parkes observations with the UWL to characterize the broadband emission properties of these sources, with the following key goals: to constrain the repetition rate, confirm any periodicity, identify the variation of pulse characteristics over time and frequency, measure the polarimetric properties and provide insight into the emission mechanism. Understanding the diverse polarization properties from these sources could be the key to distinguish repeater sources from the apparent non-repeaters ones. We have discovered several narrowband repetitions from some of these FRB sources with the UWL, demonstrating the instrument's power to identify repeats and place strong constraints on the burst emission mechanism. We will use the unique wide bandwidth observations to test leading models of burst emission for these repeating bursts.

快速射电暴（Fast Radio Bursts，FRBs）始终是未解之谜多于已知答案。在已发现的约一千个FRBs中，仅20个被证实存在重复爆发现象，其光谱时间特性暗示它们与看似不重复的爆发存在差异。重复FRB源表现出不同程度的活动性，其中两个源的重复爆发呈现周期性循环。本文拟对5个重复FRB源样本展开研究，包括ASKAP望远镜发现的FRB20171019A与FRB20190711A、Parkes望远镜发现的FRB20180301A，以及CHIME望远镜发现的FRB20201124A与FRB20190117A。我们申请使用Parkes望远镜的超宽带接收器（UWL）对这些源进行观测，以表征其宽带发射特性，核心目标如下：约束重复率、确认周期性存在与否、识别脉冲特性随时间与频率的变化、测量偏振特性，并深入探究发射机制。理解这些源的多样偏振特性或为区分重复源与看似非重复源的关键。我们已通过UWL在部分FRB源中发现若干窄带重复爆发，证明该仪器在识别重复爆发及对爆发发射机制施加严格约束方面的能力。我们将利用其独特的宽带观测数据，对这些重复爆发的主流发射模型进行验证。