Parkes observations for project P1021 semester 2021APRS_16

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.

本研究计划继续对PSR J1653-45开展观测：该脉冲星自转周期为951毫秒，处于周期长达1.5年的长轨道中，且存在暂未被完全阐明物理本质的食现象。双星脉冲星是极具科学价值的研究对象，可支撑多项前沿科研应用，包括引力理论检验、中子星物态探针以及恒星演化化石记录分析。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，属于脉冲星双星演化研究中尚未被充分探索的领域。

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。我们已在该脉冲星轨道此前未被覆盖的观测区域中探测到该天体，完成了其位置定位，并约束了食现象的起始时刻。据此，在2021APRS观测季（预计将迎来下一次食现象）开展针对性观测项目，将为阐明并理解该脉冲星提供关键突破。因此，本计划提出一项高观测频次的观测项目，其食相阶段的观测灵敏度将至少达到此前帕克斯望远镜同类观测的1.4倍。此类观测将约束食现象的终止时刻，并确保我们尽可能早且频繁地探测到该脉冲星，最终获得相位关联的计时解，从而充分释放该脉冲星的科学研究潜力。通过本项目，我们期望更深入地理解该脉冲星（及其伴星）的物理属性，并厘清其在尚未被充分探索的非再循环脉冲星双星系统类别中的演化位置。