X-ray pulsar phase-delay estimation: A Hankel-singular value decomposition subspace reconstruction approach
Phys. Rev. D 113, 063058 – Published 30 March, 2026
DOI: https://doi.org/10.1103/r6wb-vkqg
Abstract
In order to improve the performance of the x-ray pulsar timing system and further refine the pulsar time series analysis process, we propose a Hankel-singular value decomposition (SVD) principal modal vector energy-fusion based phase delay estimation method for x-ray pulsar. First, the pulsar profile signal is subjected to Hankel embedding and singular value decomposition. The principal modal vector in the structured subspace is extracted from the one-dimensional profile signal, effectively suppressing redundant components such as observation noise. Secondly, cross-spectral analysis is performed on the standard and folded profiles in the main modal domain. Combining the phase ratio method, the phase difference of each frequency component is analytically solved. By utilizing the frequency-domain phase continuity, the resolution limitation caused by discrete search in the time domain is overcome, achieving subsampling level phase delay estimation below the sampling interval. Finally, combining the frequency energy distribution characteristics of each order, we propose a fusion strategy based on cross-spectral energy constraints, using spectral amplitude to construct weights. The phase shifts of each order are weighted and adjusted to further improve estimation accuracy. Meanwhile, we conduct ablation tests, computational complexity analysis, and influencing factor analysis on the proposed method. Furthermore, we perform ground-based experimental tests using actual observation data from the NICER and XPANV-1 satellites. The results show that compared to cross-correlation estimation and maximum likelihood estimation, our method improves estimation accuracy by 26.18% and 42.72%, respectively, and improves estimation stability by 16.91% and 43.88%, respectively. The proposed method has advantages such as high estimation accuracy, strong estimation stability, and subsampling level phase estimation resolution, providing important support for the development of high-precision pulsar timing.
