Parkes observations for project P1021 semester 2019OCTS_02

We propose to conduct 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.\r\n\r\nIn 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 of 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 transition into 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.

我们提议对PSR J1653-45开展观测：该天体是一颗自转周期951毫秒的脉冲星，处于长达1.5年的长周期双星轨道中。双星脉冲星是极具科学价值的研究对象，可支撑多项前沿研究，包括引力理论检验、中子星物态方程探测以及恒星演化化石记录研究。双星系统内的长自转周期脉冲星，普遍比高速自转的“再循环”脉冲星更为稀少，且代表了脉冲星双星演化领域中一个尚未被充分探索的研究方向。

除拥有较长轨道周期外，PSR J1653-45还存在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清晰阐释。这类掩食现象还阻碍了轨道相位连接计时解的确定，而这正是持续开展该系统研究的关键前提。为此我们提议开展一项针对性高频次观测计划，旨在对该脉冲星进入掩食状态的过程进行全程监测。本观测计划兼具双重科学目标：其一为监测掩食现象对脉冲星辐射特性的影响，以此进一步揭示掩食现象的物理本质；其二为在该系统最未被探索的轨道阶段，提取尽可能多的脉冲星轨道相关信息，以此约束并有望解算出该脉冲星的轨道参数，最终促成相位连接计时解的建立。通过上述两项研究目标的达成，我们期望能够更深入地理解该脉冲星的物理特性，并明确其在尚未被充分探索的非再循环双星脉冲星类别中的学术定位。