Parkes observations for project P1021 semester 2019OCTS_07

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.

我们提议对编号为PSR J1653-45的951毫秒脉冲星（millisecond pulsar）开展观测，该天体处于轨道周期长达1.5年的长周期双星系统中。双星脉冲星（binary pulsars）是极具科研价值的观测对象，可被用于多项科学研究，包括引力理论检验、中子星物态方程（neutron star equation of state）探测以及恒星演化化石记录（fossil records of stellar evolution）分析等。双星系统中的长自转周期脉冲星，其丰度远低于快速旋转的“再循环”脉冲星（recycled pulsars），属于脉冲星双星演化研究中尚未得到充分探索的领域。

除轨道周期较长外，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，其物理本质目前尚未得到清晰阐释。此类掩食现象还阻碍了相位关联计时解（phase-connected timing solution）的确定，而这正是持续开展该双星系统研究的关键环节。我们提议实施一项针对性高时间分辨率观测计划（high-cadence observing campaign），用于监测该脉冲星进入掩食状态的过程。该观测计划兼具双重目标：其一，监测掩食对脉冲星辐射特性的影响，以此进一步揭示掩食现象的本质；其二，在该脉冲星研究程度最低的轨道阶段，提取更多关于其轨道的信息，从而约束并有望求解该脉冲星的轨道参数，最终得到相位关联计时解。通过上述两项工作，我们期望更深入地了解该脉冲星的各项属性，以及它在这一尚未被充分探索的非再循环脉冲星双星（unrecycled pulsar binaries）类别中的定位。