Parkes observations for project P1005 semester 2021APRS_09

We propose to conduct observations of PSR J1812-15, a 1-s pulsar in a 20.3-hr circular orbit around a light companion which also exhibits variable emission (turning `on’ and `off’). Binary pulsars are valuable objects of scientific study, allowing for a wide range of 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.\r\n\r\nWe propose a two-pronged campaign designed to address individual aspects of PSR J1812-15’s behaviour. Firstly, although we have developed a binary solution as a consequence of previous P1005 observations, we are still unable to develop a phase-connected timing solution, a key step in understanding this pulsar and its binary formation process. We therefore propose a 6-month monitoring campaign intended to provide the additional constraint required to determine a unique solution. Secondly, we have identified a correlation between the pulsar’s detectability and its orbital phase, suggesting that an eclipse or other complex interaction between the pulsar and its binary companion is at least partially responsible for its variable emission. We propose to monitor a series of consecutive orbits so as to fully cover the pulsar’s orbital phase, exploiting the wide bandwidth of the UWL receiver to distinguish between variability due to the binary companion or other sources (e.g. intrinsic pulse nulling).

我们提出对脉冲星PSR J1812-15开展观测研究，该天体是一颗自转周期为1秒的脉冲星，在时长20.3小时的圆轨道上围绕一颗轻量级伴星运行，且该伴星存在变辐射现象（可在“亮”与“暗”两种状态间切换）。双星脉冲星是极具科学价值的研究对象，可应用于引力检验、中子星物态方程探测以及恒星演化化石记录研究等诸多领域。双星系统中的长自转周期脉冲星通常远少于自转速度更快的再循环脉冲星，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。

我们提出一项双管齐下的观测计划，旨在解析PSR J1812-15的各项行为特征。其一，尽管通过此前的P1005观测我们已推导出双星轨道解，但仍无法获得相位连接计时解——这是理解该脉冲星及其双星形成过程的关键步骤。因此我们提议开展为期6个月的监测计划，以获取所需的额外约束条件，从而确定唯一的轨道解。其二，我们已发现该脉冲星的可探测性与其轨道相位存在相关性，这表明脉冲星与伴星之间的掩食或其他复杂相互作用，至少是其变辐射现象的部分成因。我们提议对一系列连续轨道进行监测，以完整覆盖该脉冲星的轨道相位，并利用UWL接收机（UWL receiver）的宽带宽特性，区分由双星伴星或其他来源（例如本征脉冲消隐）引发的辐射变化。