Long-term project observations for project P1361 semester 2025APRS_05

PSR J1227-6208 is a recycled pulsar in a bianry with a massive white dwarf companion. A recent timing measurement from combined MeerKAT and Parkes observations shows the companion mass to be between 1.2 and 1.5 $M_\\odot$, very close to the Chandrasekhar, resulting in potential profound physical implications. However, the timing precision is limited by the DM timing noise. We propose regular monitoring of this pulsar with the Parkes UWL receiver in conjunction with MeerKAT observations during the following four years. The joint monitoring will significantly improve the constraints on the Post-Keplerian parameters, with Parkes observations contributing to constrain the DM noise due to its large frequency bandwidth. These observations will be added to the already existing 11-year-long timing baseline, of which the later 5 years already include high-precision MeerKAT data and Parkes UWL data. After four years of further timing with the inclusion of UWL observatiosn, we predict an uncertainty on the masses smaller than 0.01 solar masses based on simulations. If UWL is not included, the mass uncertanites may saturate on their current values.

PSR J1227-6208是一颗处于双星系统中的再循环脉冲星，其伴星为大质量白矮星。近期结合MeerKAT望远镜与帕克斯（Parkes）望远镜的联合观测数据开展的计时测量结果显示，该伴星质量介于1.2至1.5倍太阳质量之间，与钱德拉塞卡（Chandrasekhar）极限极为接近，由此具备潜在的深远物理意义。然而，该计时精度受限于色散量（Dispersion Measure, DM）计时噪声。我们提出在未来四年内，利用帕克斯望远镜超宽带（Ultra-Wideband, UWL）接收机，结合MeerKAT望远镜观测对该脉冲星开展常规监测。此次联合监测将显著提升对开普勒后（Post-Keplerian）参数的约束能力，其中帕克斯望远镜凭借其较宽的频率带宽，可对色散量计时噪声形成有效约束。上述观测数据将被纳入已有的11年时长的计时基线，其中后5年的计时数据已包含高精度的MeerKAT观测数据与帕克斯望远镜超宽带观测数据。经过后续四年开展加入超宽带观测的计时工作后，基于模拟结果我们预测，该系统的质量不确定度将小于0.01倍太阳质量。若未纳入超宽带观测数据，质量不确定度可能会维持在当前水平，无法进一步降低。