Long-term project observations for project P1361 semester 2025OCTS_02

PSR J1227-6208 is a recycled pulsar in a binary 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 solar masses, very close to the Chandrasekhar limit, resulting in potentially 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 observations, we predict an uncertainty on the masses smaller than 0.01 solar masses based on simulations. If UWL is not included, the mass uncertainties may not improve beyond their current values.

PSR J1227-6208是一颗处于双星系统中的再循环脉冲星（recycled pulsar），其伴星为大质量白矮星。近期结合MeerKAT与帕克斯（Parkes）望远镜观测数据得到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，非常接近钱德拉塞卡极限（Chandrasekhar limit），具有潜在的深远物理意义。然而，计时精度受到色散量（DM）计时噪声的制约。我们提议在未来四年内，利用帕克斯UWL接收机（UWL receiver）结合MeerKAT观测对该脉冲星开展定期监测。本次联合监测将显著提升对后开普勒参数（Post-Keplerian parameters）的约束能力，其中帕克斯望远镜凭借其较宽的频率带宽，可有效约束色散量噪声。上述观测将被纳入已有的11年计时观测基线，该基线的后5年数据已包含高精度的MeerKAT观测数据与帕克斯UWL观测数据。基于模拟分析，我们预测：在额外开展四年包含UWL观测的计时项目后，质量测量的不确定度将小于0.01倍太阳质量；若未采用UWL观测，质量不确定度则无法实现显著改善，将维持在当前水平。