Parkes observations for project P1021 semester 2020OCTS_05

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.

我们提议继续对PSR J1653-45开展观测，该天体是一颗自旋周期951毫秒、轨道周期长达1.5年的脉冲星，会出现表观食现象，其持续时长与物理本质尚未得到完全阐明。双星脉冲星是极具科研价值的观测对象，可应用于诸多研究方向，包括引力检验、中子星物态方程的探测，以及恒星演化的化石记录研究。相较于自转更快的“再循环”脉冲星，双星系统中的长自旋周期脉冲星通常更为罕见，且代表了脉冲星双星演化领域中尚未被充分探索的研究方向。

基于此前帕克斯（Parkes）的观测提案，我们对该脉冲星的认知已得到显著提升。我们已在其轨道此前未被探索的区域中探测到该脉冲星，并对食现象的持续时长进行了约束；因此，在2021APRS观测学期（预计下一次食现象发生的时段）开展针对性观测计划，将为破解并理解该脉冲星的相关问题提供关键突破。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现有数据集实现成功的相位连接，从而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得精确计时解的各类短期辐射变化。通过上述工作，我们期望能更深入地理解该脉冲星的物理特性，以及它在这一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。