Long-term project observations for project P1361 semester 2025OCTS_09

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.

脉冲星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。近期基于MeerKAT射电望远镜阵列（MeerKAT）与帕克斯射电望远镜（Parkes）联合观测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（solar masses）之间，十分接近钱德拉塞卡极限（Chandrasekhar limit），这一结果具备潜在的深远物理意义。然而，该脉冲星的计时精度受色散测量（DM）计时噪声（DM timing noise）的限制。我们提议在未来四年内，利用帕克斯望远镜超宽带（UWL）接收机对该脉冲星开展定期监测，并同步开展MeerKAT观测。此次联合观测将显著提升对开普勒后参数（Post-Keplerian parameters）的约束能力；由于帕克斯望远镜具备较宽的频率带宽（frequency bandwidth），其观测数据可用于约束色散测量计时噪声。上述观测将被纳入已有的11年计时基线（timing baseline），该基线的后5年时段已包含高精度的MeerKAT观测数据与帕克斯UWL观测数据。基于模拟结果，我们预测在加入UWL观测并开展四年的后续计时观测后，质量测量的不确定度将小于0.01倍太阳质量（solar masses）。若不纳入UWL观测数据，质量测量的不确定度将无法突破当前水平。