Parkes observations for project P1021 semester 2021OCTS_01

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. Based 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.

我们提议继续对PSR J1653-45与PSR J1812-15开展观测，这两颗长自转周期双星脉冲星均表现出一定程度的轨道依赖变异性。双星脉冲星是极具科研价值的观测对象，可应用于多项研究，包括引力检验、中子星物态方程探测以及恒星演化化石记录研究。双星系统中的长自转周期脉冲星，通常远少于自转更快的再循环脉冲星（recycled pulsars），且是脉冲星双星演化领域中尚未得到充分探索的方向。这一点在PSR J1812-15上体现得尤为突出，目前仅发现另一颗脉冲星B1718-19与其勉强可比。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位置的认知已大幅提升，预计相关成果将于2022年初发表。因此，我们提议开展一项低观测频次的观测计划，以完成两颗脉冲星的计时观测收尾工作。针对PSR J1812-15，本次观测数据将有助于解决当前存在的相位连接问题——该问题可能由未被诊断的自转突变（glitch）或其他未建模计时效应引发。针对PSR J1653-45，本次数据既可充分利用2021年APRS观测计划（在食相阶段探测到该脉冲星）的突破成果，也可在其科学价值足够的前提下，为未来的食相观测计划奠定基础。这些观测是确保该双星脉冲星相关成果近期得以发表的必要最后一步。