Parkes observations for project P1021 semester 2020OCTS_08

We propose to continue our observations of PSR J1653-45, a 951-ms pulsar in a long, 1.5-yr orbit, and experiences apparent eclipses whose duration and nature have yet to be fully understood. Binary pulsars are valuable objects of scientific study, allowing for a wide range of applications, including tests of gravity, probes of the neutron star equation of state, and fossil records of stellar evolution. Long spin-period pulsars in binary systems are generally much rarer than faster-spinning `recycled’ pulsars, and represent an under-explored region of pulsar binary evolution.\r\n\r\nBased upon previous Parkes proposals, our understanding of this pulsar has significantly increased. We have detected the pulsar in previously unexplored regions of its orbit, and have constrained the duration of the eclipse, such that a targeted campaign in the 2021APRS semester (during which the next eclipse is expected) will provide the breakthrough needed to solve and understand this pulsar. For the 2020OCTS semester, we propose a lower-cadence monitoring campaign, intended to allow these future observations to be successfully-phase connected with the existing dataset, maximising their scientific utility. We also propose to conduct a small set of high-cadence observations of PSR J1653-45 intended to characterise its emission and explore any short-term variability which may be inhibiting our ability to determine a timing solution. Through this, we hope to gain a greater understanding of this pulsar’s properties and how it fits into this under-explored class of unrecycled pulsar binaries.

本研究提议继续对PSR J1653-45开展观测：该天体为一颗自转周期951毫秒的脉冲星（pulsar），处于1.5年的长周期轨道中，且存在尚未完全明确持续时长与物理本质的表观掩食现象。双星脉冲星是极具科研价值的研究对象，可支撑诸多前沿科学应用，包括引力理论检验、中子星物态方程探测以及恒星演化化石记录研究。双星系统中的长自转周期脉冲星，通常远比自旋更快的“再循环”脉冲星更为罕见，属于脉冲星双星演化领域中尚未被充分探索的研究范畴。

基于此前帕克斯（Parkes）望远镜的观测提案，我们对该脉冲星的认知已得到显著提升：我们在该脉冲星轨道此前未被探索的区域中探测到了其信号，并对掩食的持续时长进行了约束。因此，在预计将出现下一次掩食的2021APRS观测学期开展针对性观测计划，将为破解并深入理解该脉冲星提供所需的突破性进展。针对2020OCTS观测学期，我们提议开展低频次监测计划，旨在使未来的观测能够与已有数据集实现精准相位连接，最大化其科学应用价值。此外，我们还提议对PSR J1653-45开展一组小型的高频次观测，以表征其辐射特性，并探究可能阻碍我们获取精确计时解的短期辐射变化。通过上述工作，我们期望能够更深入地理解该脉冲星的物理特性，以及它在尚未被充分探索的非再循环双星脉冲星类别中所处的位置。