Parkes observations for project P1021 semester 2021APRS_11

We propose to continue our observations of PSR J1653-45, a 951-ms pulsar in a long, 1.5-yr orbit, which experiences apparent eclipses whose nature have yet to be fully understood. Binary pulsars are valuable objects of scientific study, allowing for multiple 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 and ATCA proposals, our understanding of this pulsar has significantly increased. We have detected the pulsar in previously unexplored regions of its orbit, localised its position, and have constrained the start 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. We therefore propose a high-cadence campaign with observations at least 1.4 times more sensitive than any previously recorded with Parkes during the eclipse. These observations will constrain the end of the eclipse and ensure that we detect the pulsar as early and often as possible, leading to a phase connected timing solution which will unlock the pulsar’s scientific potential. Through this, we hope to gain a greater understanding of this pulsar’s properties (as well as those of its companion) and how it fits into this under-explored class of unrecycled pulsar binaries.

我们提出继续对脉冲星PSR J1653-45开展观测：该天体自转周期为951毫秒，处于1.5年的长周期双星轨道中，存在疑似食现象，其本质尚未完全阐明。双星脉冲星是极具科学价值的研究对象，可应用于多项前沿研究方向，包括引力检验、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，通常远少于自转更快的“再循环”脉冲星，代表了脉冲星双星演化研究中尚未被充分探索的领域。

基于此前针对帕克斯望远镜（Parkes）与澳大利亚望远镜致密阵列（Australia Telescope Compact Array, ATCA）的观测提案，我们对该脉冲星的认知已显著提升。我们已在该脉冲星轨道此前未被探索的区域中探测到它，完成了高精度位置定位，并对食现象的起始时间施加了严格约束。因此，在2021APRS观测时段（预计将迎来下一次食现象）开展针对性观测计划，将为阐明该脉冲星的本质取得关键性突破。据此，我们提出一项高频次观测计划，其观测灵敏度至少比此前帕克斯望远镜在该食现象期间的观测结果高1.4倍。此类观测将对食现象的结束时间施加严格约束，并确保我们尽可能早且频繁地探测到该脉冲星，从而获得相位关联的计时解，充分释放该脉冲星的科学研究潜力。通过此项研究，我们希望进一步明晰该脉冲星（及其伴星）的物理特性，并厘清其在尚未被充分探索的非再循环双星脉冲星类别中的演化位置。