Parkes observations for project P1068 semester 2021APRS_22

In the fast-moving world of Fast Radio Bursts (FRBs), the critical question of what fraction of FRBs emit repeat bursts remains unanswered. Of order 20 repeating FRBs are now known, and their spectro-temporal properties hint at differences with apparently non-repeating bursts - the poor statistics preclude a definitive diagnosis. FRB 180301 is a promising source for further study for multiple reasons: it is an active repeater similar to the FRB 121102 and the most active FRB source visible to Parkes, and it shows diverse polarization properties across the repeat bursts. We have detected multiple repeat bursts from this source in our campaign last semester. The signal-to-noise ratio (S/N) of these detections are not sufficiently significant to measure their spectro-polarimetric properties. We request Parkes observations with the UWL receiver to continue the monitoring of this FRB source in order to characterize the broadband emission properties. Some of the key goals for these future observations are: to constrain the repetition rate, identify any variation of pulse characteristics over time, measure the polarimetric properties and provide insight into the emission mechanisms. The diverse polarization angle swings in the FAST detections and significant circular polarization in the original Parkes detection indicate the progenitor is embedded in an extreme magneto-ionic environment with complex field structure that has not been seen before. Understanding these diverse polarization properties from this source could be the key to distinguish repeater sources from the apparent non-repeaters ones.

在快速射电暴（Fast Radio Bursts, FRBs）这一飞速发展的研究领域中，关于有多少比例的快速射电暴会重复爆发这一关键问题至今仍未得到解答。目前已知约20个重复爆发的快速射电暴，它们的谱时特性暗示其与表观非重复暴存在差异——但受限于统计样本不足，无法做出确定性诊断。
FRB 180301是极具进一步研究价值的源，原因如下：它是与FRB 121102类似的活跃重复暴源，同时也是帕克斯（Parkes）望远镜可观测到的最活跃的快速射电暴源，且其各次重复暴均展现出多样的偏振特性。本课题组上一学期的观测计划中，我们已从该源中探测到多起重复爆发信号。此次探测的信噪比（signal-to-noise ratio, S/N）尚未达到足够高的水平，无法对其谱偏振特性开展测量。
我们申请使用搭载UWL接收机的帕克斯望远镜，继续对该快速射电暴源开展监测，以刻画其宽波段辐射特性。此次后续观测的核心目标包括：约束重复爆发率、探究脉冲特性随时间的变化、测量偏振特性，以及为辐射机制研究提供深入认知。
500米口径球面射电望远镜（Five-hundred-meter Aperture Spherical radio Telescope, FAST）探测到的多样偏振角摆动，以及初始帕克斯观测中发现的显著圆偏振特征，均表明该源的前身天体嵌于前所未见的极端磁离子环境中，且拥有复杂的磁场结构。解析该源的多样偏振特性，或将成为区分重复暴源与表观非重复暴源的关键。