Parkes observations for project P1005 semester 2021APRS_11

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：该脉冲星自转周期为1秒，以20.3小时的圆轨道环绕一颗轻质伴星运行，且该伴星自身的辐射亦存在“亮灭”切换的可变现象。双星脉冲星是极具科研价值的天体，可应用于诸多前沿研究方向，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，其数量通常远少于快速自转的再循环脉冲星，对应的双星演化区域也尚未得到充分探索。 我们提出一项双管齐下的观测计划，旨在逐一解析PSR J1812-15的行为特征。其一，尽管我们基于此前的P1005观测得到了双星轨道解，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。为此，我们提议开展为期6个月的监测计划，以获取足够的额外约束条件，从而得到唯一确定的轨道解。其二，我们发现该脉冲星的可探测性与其轨道相位存在显著相关性，这表明脉冲星与伴星之间的掩食现象或其他复杂相互作用，至少是其辐射可变的部分成因。我们提议对一系列连续轨道进行监测，以完全覆盖该脉冲星的轨道相位区间，并利用UWL接收机（UWL Receiver）的超宽带宽，区分辐射变化源自双星伴星还是其他来源（例如脉冲本征消隐）。