Parkes observations for project P1021 semester 2021APRS_05

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.我们提议继续开展对PSR J1653-45的观测研究。该天体是一颗处于1.5年长周期轨道中的951毫秒脉冲星，存在表观掩食现象，其本质尚待完全阐明。双星脉冲星是极具科研价值的天体，可应用于多项前沿研究，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分析。处于双星系统中的长自旋周期脉冲星，通常远少于自旋更快的“再循环”脉冲星，代表了脉冲星双星演化领域中尚未被充分探索的研究方向。 基于此前帕克斯（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显著提升。我们在其轨道此前未被探索的区域中成功探测到该脉冲星，定位了其精确位置，并约束了掩食的起始时刻。因此在2021APRS观测季（预计将迎来下一次掩食）开展针对性观测计划，将为破解并全面理解该脉冲星提供关键突破。我们因此提议开展高频次观测计划，其观测灵敏度至少比此前帕克斯望远镜在掩食期间的任何观测都高出1.4倍。此类观测将约束掩食的终止时刻，并确保我们尽可能早且频繁地探测到该脉冲星，从而得到相位连贯计时解，这将充分释放该脉冲星的科学研究潜力。通过此项研究，我们希望更深入地理解该脉冲星（以及其伴星）的性质，以及它如何归入这一尚未被充分探索的非再循环脉冲星双星系统类别。