Parkes observations for project P1021 semester 2021APRS_13

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.

我们提出将持续开展对PSR J1653-45的观测研究：该天体是一颗处于1.5年长轨道中的951毫秒脉冲星，其存在表观食现象，目前该现象的本质尚未被完全阐明。双星脉冲星是极具科学价值的研究对象，可应用于多项科研场景，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领域中一个尚未被充分探索的方向。

基于此前帕克斯望远镜（Parkes）与澳大利亚望远镜致密阵列（ATCA）的观测提案，我们对该脉冲星的认知已得到显著提升。我们在其轨道此前未被探索的区域中探测到了该脉冲星，精确定位了其位置，并对食现象的起始时刻施加了约束。基于此，在2021APRS观测学期（预计下一次食现象将发生于此期间）开展针对性观测计划，将为破解并阐明该脉冲星的相关问题提供关键突破。因此，我们提出开展高观测频次的观测计划，其观测灵敏度至少比此前帕克斯望远镜在食现象期间的所有记录高出1.4倍。此类观测将对食现象的终止时刻施加约束，并确保我们尽可能早且频繁地探测到该脉冲星，从而得到相位关联的计时解，进而充分释放该脉冲星的科学潜力。通过此项研究，我们期望更深入地了解该脉冲星（及其伴星）的物理属性，以及它在这一尚未被充分探索的非再循环脉冲星双星类别中所处的演化位置。