Parkes observations for project P1021 semester 2019OCTS_03

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. 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 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开展观测研究：该天体是一颗轨道周期长达1.5年的951毫秒脉冲星（pulsar）。双星脉冲星（binary pulsars）是极具科研价值的研究对象，可应用于诸多科学场景，包括引力检验、中子星物态方程（neutron star equation of state）探测以及恒星演化化石记录研究。双星系统中自旋周期较长的脉冲星，通常比快速旋转的再循环脉冲星（recycled pulsar）更为罕见，其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。除轨道周期较长外，PSR J1653-45还存在持续时长可达轨道周期一半的延展掩食，其本质目前尚未得到充分阐释。这类掩食还阻碍了我们获取该系统的相位关联轨道计时解（phase-connected timing solution），而这正是持续开展该系统研究的关键环节。我们设计了一项针对性高频率观测计划，旨在当该脉冲星进入掩食状态时对其进行监测。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，从而进一步揭示掩食本身的物理本质；其二，在该脉冲星轨道最未被探索的阶段，尽可能多地提取轨道相关信息，以此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。通过上述两项研究，我们期望能够更深入地理解该脉冲星的物理特性，以及它在这一尚未被充分探索的非再循环脉冲星双星系统类别中的定位。