Parkes observations for project P1172 semester 2023APRS_05

PSR J1713+0747 is a very important millisecond pulsar for global pulsar timing array campaigns, due to its long-term observation history, very stable and narrow profile and strong S/N. In April 2021, the pulsar experienced a significant event related to a change in its magnetosphere, presented as an observable change in the pulsar profile. Since then, the pulsar has been slowly recovering and we wish to observe this recovery with high-cadence observations to allow us to create a detailed time-resolved series of variations in the MSPs profile, polarisation, and other properties. Under this proposal, we wish to probe the profile recovery on weekly timescales (once per week per month), revealing additional short timescale behaviours, indicative of changes in the magnetosphere which are not available to other telescopes in the world, thanks to the Parkes UWL. This will also allow us to determine if the magnetosphere has returned to its original configuration or is settling into a new one. Understanding the recovery of this event is key for demonstrating that such pulsars are still viable clocks for use in gravitational wave studies, and in turn, provide us with new data on how the normally stable magnetosphere of this millisecond pulsar responds to an impulsive change in state.

PSR J1713+0747是一颗对全球脉冲星计时阵列（pulsar timing array, PTA）观测项目至关重要的毫秒脉冲星（millisecond pulsar, MSP），其拥有长期观测历史，且脉冲轮廓极稳定、宽度极窄，信噪比（Signal-to-Noise Ratio, S/N）优异。2021年4月，该脉冲星发生了一次与其磁层（magnetosphere）变化相关的重大事件，表现为脉冲星轮廓出现可观测的改变。自此之后，该脉冲星始终处于缓慢恢复状态。我们计划通过高频次观测对这一恢复过程开展监测，以获取该毫秒脉冲星轮廓、偏振（polarisation）及其他属性的详细时间分辨变化序列。依托本观测提案，我们拟以周为时间尺度开展观测（每月内每周一次），从而揭示此前未被捕捉到的短时标行为特征——这类特征可反映磁层的变化，而这类变化是全球其他望远镜无法观测到的，这得益于帕克斯望远镜的Parkes UWL设备。这一观测计划还将帮助我们判断该脉冲星的磁层是否已恢复至初始构型，或是正逐渐稳定至新的稳定状态。阐明此次事件的恢复过程，是证明此类脉冲星仍可作为引力波（gravitational wave）研究中可靠计时工具的关键；同时也将为我们揭示这颗通常状态稳定的毫秒脉冲星的磁层如何响应状态的突发性改变，提供全新的观测数据。