Parkes observations for project P1021 semester 2022OCTS_10

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.

我们提议观测PSR J1812-15和PSR J1831-04这对长自旋周期双星脉冲星（binary pulsars），二者均表现出一定程度的轨道相关变异性。双星脉冲星是极具价值的科学研究对象，可应用于多个领域，包括引力测试、中子星状态方程探测以及恒星演化的化石记录。双星系统中的长自旋周期脉冲星通常比自转更快的“再生脉冲星（recycled pulsars）”稀少得多，且代表了脉冲星双星演化中尚未充分探索的区域。PSR J1812-15尤其如此，目前仅有另一颗脉冲星（B1718-19）与之存在微弱可比性；而PSR J1831-04或许会成为该类别的第三个成员。

我们对两颗脉冲星的观测目标有所不同。对于PSR J1812-15，仍需开展最低限度的低cadence计时观测（low-cadence timing campaign）以解决持续存在的相位连接（phase connection）问题——该问题可能由未诊断的星震事件（glitch）或其他未建模的计时效应所致。除此之外，该源的独特性使其值得进一步监测，以防出现更多未记录的行为。对于PSR J1831-04（迄今为止仅被探测到一次），我们的观测计划旨在通过随机观测时间表提供重新探测该脉冲星的最佳机会，从而表征该脉冲星及其双星系统。若其被证实与PSR J1812和B1718相似，则将极大促进我们对这类稀有双星脉冲星的理解。