Parkes observations for project P1021 semester 2021OCTS_06

We propose to continue our observations of PSR J1653-45 and PSR J1812-15, a pair of long spin-period binary pulsars which both show degrees of orbitally-dependent variability. Binary pulsars are valuable objects of scientific study, allowing for multiple 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. This is particularly true of PSR J1812-15, for which only one other pulsar (B1718-19) seems remotely comparable.\r\n\r\nBased upon previous Parkes proposals, our understanding of these pulsars and their place with binary evolution has significantly increased, such that we anticipate their publication in early 2022. We therefore propose a low-cadence campaign intended to finalise the timing of both pulsars. For PSR J1812-15, this data will be useful in addressing on-going problems with phase connection, which may be caused by an undiagnosed glitch or other un-modeled timing effect. For PSR J1653-45, this data will be useful in both capitalising on the breakthroughs of the 2021APRS campaign (detection of the pulsar during its eclipse phase) and in setting up a future eclipse campaign should it be deemed of sufficient scientific merit. These observations are the final step needed to ensure the publication of these pulsars in the immediate term.

我们提议继续开展对脉冲星PSR J1653-45与PSR J1812-15的观测工作，这是一对长自旋周期双星脉冲星（binary pulsars），二者均呈现出轨道依赖性变异性特征。双星脉冲星是极具科研价值的观测对象，可支撑多项研究应用，包括引力检验、中子星物态方程（equation of state）探针以及恒星演化化石记录研究。长自旋周期双星脉冲星的数量普遍远少于快速旋转的“再循环”脉冲星（recycled pulsars），其代表了脉冲星双星演化领域中尚未被充分探索的研究方向，这一点在PSR J1812-15上体现得尤为突出——目前仅脉冲星B1718-19能勉强与之类比。
基于此前的帕克斯（Parkes）观测提案，我们对这两颗脉冲星及其在双星演化中的定位的认知已得到显著提升，相关研究成果预计将于2022年初发表。因此我们提议开展低频次观测计划，以最终完成两颗脉冲星的计时观测工作。针对PSR J1812-15，本次观测数据将有助于解决当前存在的相位关联难题，该问题可能由未被诊断的自转突变（glitch）或其他未建模的计时效应所引发。针对PSR J1653-45，本次观测数据既可用于巩固2021年APRS观测计划中取得的突破——即在其食相阶段成功探测到该脉冲星，也可在经评估具备足够科学价值后，为后续的食相观测计划奠定基础。上述观测是确保该类脉冲星研究成果快速发表所需的最后一步。