Parkes observations for project P1021 semester 2020APRS_07

We propose to continue our observations of PSR J1653-45, a 951-ms pulsar in a long, 1.5-yr orbit. Binary pulsars are valuable objects of scientific study, allowing for a wide range of 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. In addition to its long orbital period, PSR J1653-45 also experiences extended eclipses, lasting up to half of the orbital period and whose nature is not well understood. These eclipses have also prevented the determination of an orbital or phase-connected timing solution, both vital steps in allowing for the continued study of this system. We propose a targeted, high-cadence observing campaign designed to monitor this pulsar as it transitions out of its eclipsing state. The campaign has the twin goals of both monitoring how the eclipse affects the pulsar’s emission properties, thereby revealed more about the nature of the eclipses themselves, and of extracting as much information regarding the pulsar’s orbit during its least-explored regions, thereby constrained and hopefully solving the pulsar’s orbit and ideally leading to the development of a timing solution. In both instances, we hope to gain a greater understanding of this pulsar’s properties and how it fits into this under-explored class of unrecycled pulsar binaries.

我们提出将继续开展对PSR J1653-45的观测工作，该天体是一颗处于1.5年长轨道周期中的951毫秒脉冲星。双星脉冲星（binary pulsars）是极具科学研究价值的目标对象，可应用于诸多前沿研究领域，包括引力理论检验、中子星状态方程（neutron star equation of state）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，通常远少于自转速度更快的再循环脉冲星（recycled pulsars），属于脉冲星双星演化领域中尚未被充分探索的研究范畴。除拥有较长的轨道周期外，PSR J1653-45还会出现持续时长可达轨道周期一半的长时掩食现象，其本质目前尚未得到充分阐释。这类掩食现象还阻碍了轨道解与相位关联计时解（phase-connected timing solution）的确定，而这两者均是持续开展该系统研究的关键步骤。我们提出一项针对性的高频率观测项目（high-cadence observing campaign），旨在监测该脉冲星从掩食状态中过渡的全过程。该计划兼具双重目标：一是监测掩食如何影响脉冲星的辐射特性，以此进一步揭示掩食现象的本质；二是在该系统掩食阶段这一最少被探索的时段中，尽可能多地提取有关该脉冲星轨道的信息，从而约束并有望求解该脉冲星的轨道参数，最终实现相位关联计时解的构建。无论从上述哪一目标出发，我们都希望能够更深入地了解这颗脉冲星的各项特性，以及它在这一尚未被充分研究的非再循环脉冲星双星类别中的定位。