Parkes observations for project P1021 semester 2021APRS_22

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.

本研究拟继续开展对PSR J1653-45的观测：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，且存在尚未完全阐明其本质的表观掩食现象。双星脉冲星（binary pulsar）是极具科研价值的天体，可应用于多项研究方向，包括引力检验、中子星物态方程探针以及恒星演化的化石记录。双星系统中长自转周期脉冲星，相较于快速自转的“再循环”脉冲星（recycled pulsar）更为稀有，其所属的脉冲双星演化区域目前仍有待深入探索。

基于帕克斯望远镜（Parkes）与澳大利亚紧凑阵列望远镜（ATCA）的前期观测提案，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探索的区域中探测到其信号，完成了位置精确定位，并对掩食起始时刻进行了约束。基于上述成果，在2021APRS学期（预计将迎来下一次掩食）开展针对性观测计划，将为阐明该脉冲星的本质取得突破性进展。因此，我们拟开展高时间分辨率观测计划，其观测灵敏度相较于帕克斯望远镜此前针对该掩食事件的所有记录至少提升1.4倍。此类观测将对掩食结束时刻进行约束，并确保我们尽可能早且频繁地探测到该脉冲星信号，最终获得相位关联的计时解，从而充分挖掘该脉冲星的科研潜力。通过本计划，我们期望更深入地阐明该脉冲星（及其伴星）的物理属性，并明确其在尚未被充分探索的非再循环脉冲双星家族中的演化位置。