Parkes observations for project P996 semester 2019APRS_06

We propose to measure the polarisation of 107 southern pulsars (distance>5kpc. 77 in this semester) using the Ultra-Wideband Low (UWL) receiver to investigate the structure of the Galactic disk magnetic field in and between distant spiral arms. Previous Parkes pulsar observations have revealed field reversals in nearby arm and interarm regions. We wish to exploit the greater sensitivity of the UWL receive r to extend this to more distant regions, thereby allowing us to distinguish more clearly between different models for the structure of the disk field. Because of the intrinsic uncertainty in DM-based pulsar distances, averaging data over groups of pulsars is necessary to confidently demonstrate any magnetic-field reversals. This work will have important implications for theories for the generation of Galactic magnetic fields and for other areas, e.g., cosmic-ray physics, which depend on a knowledge of the large-scale Galactic magnetic field for their interpretation.

我们提出利用超宽频带低频（Ultra-Wideband Low, UWL）接收机，对107颗南天脉冲星（距离＞5千秒差距，其中77颗将于本观测周期内完成观测）的偏振特性开展测量，以研究遥远旋臂内部及旋臂间的银盘磁场结构。此前的帕克斯（Parkes）脉冲星观测已在邻近旋臂及臂间区域中发现了磁场反转现象。我们期望借助UWL接收机更高的灵敏度，将该研究拓展至更遥远的区域，从而能够更清晰地分辨银盘磁场结构的不同模型。由于基于色散量（Dispersion Measure, DM）的脉冲星距离存在固有不确定性，我们需要对多组脉冲星的数据进行平均处理，才能确凿地验证磁场反转现象的存在。本研究将对银盘磁场生成理论以及其他依赖大尺度银盘磁场知识开展解释的研究领域（例如宇宙线物理学）产生重要意义。