Parkes observations for project P1021 semester 2021APRS_10

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. Based 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.

我们提议继续对PSR J1653-45开展观测：该天体是一颗处于1.5年长轨道中的951毫秒脉冲星，存在表观掩食现象，其本质尚未完全阐明。双星脉冲星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，远少于自转更快的"再循环"脉冲星，属于脉冲星双星演化领域中尚未被充分探索的研究范畴。基于此前帕克斯（Parkes）望远镜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，并对掩食的起始时刻进行了约束。因此，在2021年APRS观测周期（预计将迎来下一次掩食）开展针对性观测，将为破解并理解这颗脉冲星提供关键性突破。据此我们提出一项高采样率观测计划，其观测灵敏度至少比此前帕克斯望远镜在掩食期间的所有观测记录高1.4倍。本次观测将对掩食的终止时刻进行约束，并确保我们尽可能早且频繁地探测到该脉冲星，从而获得相位连接计时解，充分释放该脉冲星的科研潜力。通过本次观测，我们期望更深入地理解该脉冲星（及其伴星）的物理性质，以及它在这一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。