Millisecond pulsars (MSPs) are known for their long-term stability. Using six years of observations from the Neutron Star Interior Composition Explorer (NICER), we have conducted an in-depth analysis of the X-ray timing results for six MSPs: PSRs B1937+21, B1821−24, J0437−4715, J0030+0451, J0218+4232, and J2124−3358. The timing stability parameter σz has been calculated, revealing remarkable timing precision on the order of 10−14 for PSRs B1937+21 and J0437−4715, and 10−13 for PSRs B1821−24, J0218+4232, and J0030+0451 over a timescale of 1000 days. These findings underscore the feasibility of autonomous in-orbit timekeeping using X-ray observations of MSPs. In addition, the consistency of long-term spin-down noise in the X-ray and radio bands has been investigated by comparison with IPTA radio data.
@article{arxiv.2404.16263,
title = {New Timing Results of MSPs from NICER Observations},
author = {Shijie Zheng and Dawei Han and Heng Xu and Kejia Lee and Jianping Yuan and Haoxi Wang and Mingyu Ge and Liang Zhang and Yongye Li and Yitao Yin and Xiang Ma and Yong Chen and Shuangnan Zhang},
journal= {arXiv preprint arXiv:2404.16263},
year = {2024}
}