Long-term project observations for project P1361 semester 2025APRS_03

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（recycled pulsar），其伴星为大质量白矮星。近期结合米尔卡特（MeerKAT）与帕克斯（Parkes）望远镜的联合观测数据开展的计时分析显示，该脉冲星的伴星质量介于1.2至1.5倍太阳质量（$M_odot$）之间，十分接近钱德拉塞卡（Chandrasekhar）质量极限，该结果具备潜在的重大物理意义。然而，当前计时精度受限于色散量（DM）计时噪声。我们提议在未来四年内，采用帕克斯望远镜的超宽频带（UWL）接收机对该脉冲星开展常规监测，并同步配合米尔卡特望远镜的观测工作。此次联合观测将显著提升开普勒后（Post-Keplerian）参数的约束精度：帕克斯望远镜凭借其超大频率带宽，可有效约束色散量噪声。本次新增观测将被纳入已有的11年时长计时基线，其中该基线的后5年已包含高精度的米尔卡特望远镜观测数据与帕克斯UWL接收机观测数据。基于模拟分析，我们预测：在新增四年的UWL接收机计时观测后，该伴星质量的测量不确定度将优于0.01倍太阳质量。若不采用UWL接收机开展观测，伴星质量的测量不确定度将维持在当前水平，无法得到进一步优化。