Parkes observations for project P1068 semester 2021APRS_05

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）快速发展的研究领域中，一个核心未解问题是：有多大比例的快速射电暴会重复爆发。目前已知约20个重复暴源，它们的谱时特性暗示其与非重复暴存在差异，但受限于统计数据不足，无法给出确定性结论。
FRB 180301是极具进一步研究价值的目标源，原因如下：其一，它与FRB 121102同属活跃重复暴源，同时也是帕克斯（Parkes）望远镜可观测到的最活跃快速射电暴源；其二，其多次爆发展现出多样的偏振特性。
在上一学期的观测项目中，我们已从该源中探测到多次重复爆发，但此次探测的信噪比（signal-to-noise ratio, S/N）不足以支撑对其谱偏振特性的测量。为此我们申请使用帕克斯望远镜搭载的UWL接收机开展观测，以持续监测该快速射电暴源，从而刻画其宽波段辐射特性。
本次后续观测的核心目标包括：限定重复爆发率，探究脉冲特性随时间的演化规律，测量偏振特性，并为揭示辐射机制提供关键线索。
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，均表明该暴源的前身星嵌入于前所未有的极端磁离子环境中，且具备复杂的磁场结构。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突破口。