Parkes observations for project P1021 semester 2020APRS_05

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.

我们提议继续观测PSR J1653-45——一颗自旋周期为951毫秒、轨道周期长达1.5年的脉冲星。双星脉冲星（binary pulsars）是极具科学研究价值的天体，其应用场景广泛，涵盖引力测试、中子星状态方程探测以及恒星演化的化石记录等领域。双星系统中的长自旋周期脉冲星通常远少于转速更快的“再生”脉冲星，且代表了脉冲星双星演化中尚未充分探索的领域。除长轨道周期外，PSR J1653-45还存在持续时间长达轨道周期一半的长时间掩食现象，其本质尚未被充分理解。这些掩食现象也阻碍了轨道计时解或相位关联计时解的确定，而这两者是持续研究该系统的关键步骤。我们提议开展一项针对性的高频率观测计划，旨在监测该脉冲星从掩食状态过渡的过程。该计划具有双重目标：一是监测掩食对脉冲星辐射特性的影响，从而揭示掩食现象本身的本质；二是提取该脉冲星在其探索最少区域的轨道信息，从而约束并有望解算其轨道，理想情况下还能推进计时解的建立。通过这两方面的研究，我们希望能更深入地理解该脉冲星的特性，以及它在这一尚未充分探索的非再生脉冲星双星类别中的位置。