Parkes observations for project P1021 semester 2022OCTS_08

We propose to observe PSR J1812-15 and PSR J1831-04, 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 underexplored region of pulsar binary evolution. This is particularly true of PSR J1812-15, for which only one other pulsar (B1718-19) seems remotely comparable, while PSR J1831-04 may yet turn out to be a third member of this class\r\n\r\nOur objectives differ for each pulsar. For PSR J1812-15, a minimal low-cadence timing campaign is still required to address ongoing problems with phase connection, which may be caused by an undiagnosed glitch or other un-modelled timing effect. Beyond this, the utter uniqueness of the source warrants further monitoring in the event it displays further undocumented behaviour. For PSR J1831-04 (to date detected only once), our campaign is designed to provide the optimal chance of redetecting the pulsar through a randomised observing schedule, thereby characterising the pulsar and its binary system. If confirmed as similar to PSRs J1812 and B1718, it would contribute significantly to our understanding of this rare class of binary pulsar.

本研究拟对脉冲星PSR J1812-15与PSR J1831-04开展观测，二者均为长自旋周期双星脉冲星（binary pulsars），且均表现出不同程度的轨道依赖变异性。双星脉冲星是极具科学价值的研究对象，可应用于多项研究方向，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。双星系统中的长自旋周期脉冲星，通常远比快速自旋的“再循环”脉冲星（recycled pulsars）更为稀有，且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上体现得尤为明显：目前仅发现脉冲星B1718-19可与其勉强类比；而PSR J1831-04则有可能成为该类天体的第三个成员。

针对两颗脉冲星，本研究的观测目标各有侧重。针对PSR J1812-15，仍需开展最低限度的低频次计时观测计划，以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。除此之外，该脉冲星的绝对独特性也要求我们开展进一步监测，以应对其出现未被记录的新行为的可能性。而对于截至目前仅被探测到一次的PSR J1831-04，本观测计划旨在通过随机化观测日程最大化重新探测到该脉冲星的概率，进而完成对该脉冲星及其双星系统的特性表征。若后续证实其与PSR J1812及B1718属于同类天体，将极大推动我们对这类稀有双星脉冲星的认知。