New Timing Results of MSPs from NICER Observations

TL;DR

This paper analyzes six years of NICER X-ray data on six millisecond pulsars, demonstrating their exceptional timing stability and potential for autonomous space-based timekeeping, and compares X-ray and radio timing noise.

Contribution

It provides new long-term X-ray timing results for six MSPs, highlighting their stability and consistency with radio data, supporting their use in autonomous in-orbit timing.

Findings

Timing stability of ~10^{-14} for some MSPs over 1000 days

Feasibility of X-ray MSPs for autonomous space timekeeping

Long-term spin-down noise consistent across X-ray and radio bands

Abstract

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 $\sigma_z$ 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.