Parkes observations for project P1334 semester 2024OCTS_01

The Galactic Centre is the most complex and dynamic region of our Galaxy. Radio images have revealed a plethora of filamentary structures that trace out magnetic fields running perpendicular to the Galactic plane. Exactly what powers the radio emission of these filaments had remained a mystery, until the serendipitous discovery of a pulsar embedded in one. With a spin-period of 8.4 ms, PSR J1744-2946 is the first ever millisecond pulsar to be discovered in the central region of our Galaxy. While an exciting discovery in its own right, the limited timing baseline leaves open several unanswered questions: How efficiently is the pulsar injecting energy into the radio filament? Could the pulsar be included in pulsar timing array experiments? And can it be used as a key component in the search for axion dark matter? In this proposal we will use the Ultra-Wideband Low receiver system on Murriyang to conduct regular, monthly observations of PSR J1744-2946. This will provide us with a measurement of the pulsar spin-down rate and a sense of its long-term stability, thereby providing answers to the questions posed above.

银河系中心 (Galactic Centre) 是银河系中最为复杂且动态多变的区域。射电图像 (radio images) 已揭示出大量纤维状结构 (filamentary structures)，这些结构勾勒出垂直于银道面 (Galactic plane) 分布的磁场。长期以来，这些纤维状结构的射电辐射能源究竟为何始终是未解之谜，直到人们在其中一处纤维结构中偶然发现了一颗脉冲星 (pulsar)。这颗自转周期为8.4毫秒的毫秒脉冲星 (millisecond pulsar) PSR J1744-2946，是人类在银河系中心区域发现的首颗此类天体。尽管这一发现本身已足够令人振奋，但受制于有限的计时基线 (timing baseline)，仍有多个悬而未决的问题：该脉冲星向射电纤维结构注入能量的效率究竟有多高？该脉冲星能否被纳入脉冲星计时阵列 (pulsar timing array) 实验？它能否作为关键组分用于轴子暗物质 (axion dark matter) 的搜寻工作？本提案计划利用Murriyang望远镜上的超宽带低频段接收机系统 (Ultra-Wideband Low receiver system)，对PSR J1744-2946开展每月一次的常规观测。此次观测将帮助我们测得该脉冲星的自转减速率 (spin-down rate)，并掌握其长期稳定性特征，从而为前述所有问题提供解答。