Parkes observations for project P1021 semester 2022OCTS_06

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这一对长自转周期双脉冲星，二者均表现出一定程度的轨道依赖性变异性。双脉冲星是极具价值的科学研究对象，其应用场景广泛，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等。双星系统中的长自转周期脉冲星通常比转速更快的“再生脉冲星（recycled pulsars）”稀有得多，且代表了脉冲星双星演化中一个未被充分探索的领域。PSR J1812-15的情况尤其如此，目前仅有另一颗脉冲星（B1718-19）与其存在微弱可比性，而PSR J1831-04或可成为该类别的第三个成员。

我们针对每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频率计时观测计划，以解决当前相位连接存在的问题——这些问题可能由未诊断的脉冲星自转突变或其他未建模的计时效应导致。除此之外，鉴于该源的独特性，若其出现更多未被记录的行为，进一步监测是必要的。对于PSR J1831-04（迄今仅被探测到一次），我们的观测计划通过随机观测时间表设计，旨在最大化重新探测到该脉冲星的概率，进而表征其自身及双星系统的特性。若证实其与PSR J1812和B1718相似，则将极大促进我们对这一稀有双脉冲星类别的理解。