Parkes observations for project P1168 semester 2023OCTS_01

We discovered seven pulsars in the globular cluster Terzan 1 with the Green Bank Telescope (GBT), the first pulsars to be found in this cluster. The discoveries include five fully-recycled millisecond pulsars (MSPs) with spin periods between 3 and 6 ms, an 11-ms MSP, and a pulsar with an unusually long spin period of 134 ms. Our preliminary timing suggested that all seven are likely isolated pulsars, consistent with Terzan 1 being a core-collapsed globular cluster. The 134-ms pulsar is an especially interesting discovery in the context of pulsar formation via electron-capture rather than core-collapse supernovae. In 2022OCT we observed Terzan 1 with Parkes three times and confirmed that all pulsars could be detected. We began a year-long timing campaign in the present semester, 2023APR, and were granted continuing status for that campaign. We request to continue timing these pulsars through 2023OCT. To refine the timing parameters and probe the pulsars' acceleration in the cluster potential, we will extend phase connection beyond one year using the 2022OCT observations, and we will attempt to phase connect back to the original GBT discovery pointings. In addition to timing, we will probe the pulsars' polarization properties and the Galactic magnetic field in the direction of Terzan 1; and the proposed observations will also be searched for new pulsars that may have been missed in previous observations.

我们利用绿岸望远镜（Green Bank Telescope, GBT）在球状星团Terzan 1中发现了7颗脉冲星，这是该星团中首次被发现的脉冲星。此次发现包含5颗完全再循环的毫秒脉冲星（millisecond pulsars, MSPs），其自转周期介于3至6毫秒之间，1颗自转周期为11毫秒的毫秒脉冲星，以及1颗自转周期异常长的134毫秒脉冲星。我们的初步计时分析显示，这7颗脉冲星大概率均为孤立脉冲星，这与Terzan 1属于核塌缩球状星团的结论相符。其中134毫秒脉冲星的发现尤为引人关注，因为它可为通过电子俘获而非核塌超新星形成脉冲星的理论提供支撑。我们于2022年10月使用帕克斯望远镜（Parkes）对Terzan 1进行了三次观测，确认了所有脉冲星均可被探测到。我们在2023年4月开启了为期一年的计时观测项目，并获得了该项目的延续资格。我们申请将该计时观测项目延续至2023年10月。为优化计时参数并探究脉冲星在星团势场中的加速度，我们将利用2022年10月的观测数据将相位连接时长延长至一年以上，同时尝试回溯至最初利用绿岸望远镜开展发现观测的时段进行相位连接。除计时观测外，我们还将研究脉冲星的偏振特性以及Terzan 1方向的银河磁场；本次申请的观测计划还将用于搜寻此前观测中可能遗漏的新脉冲星。