Building X-ray pulsar timing model without the use of radio parameters. (February 2018)

• Record Type: Journal Article
• Authors: Sun, Hai-feng; Sun, Xiong; Fang, Hai-yan; Shen, Li-rong; Cong, Shao-peng; Liu, Yan-ming; Li, Xiao-ping; Bao, Wei-min
• Is Part Of: Acta astronautica. Volume 143(2018)
• Page Start: 155
• Page End: 162
• Publication Date: 2018-02
• Subjects: X-ray pulsar navigation -- X-ray timing model -- Crab pulsar -- RXTE satellite -- XPNAV-1 satellite; Astronautics -- Periodicals; Outer space -- Exploration -- Periodicals; Astronautics; Periodicals; 629.405
• DOI: 10.1016/j.actaastro.2017.11.014
• Languages: English
• ISSNs: 0094-5765

Abstract

Abstract: This paper develops a timing solution for the X-ray pulsar timing model without the use of the initial radio model parameters. First, we address the problem of phase ambiguities for the pre-fit residuals in the construction of pulsar timing model. To improve the estimation accuracy of the pulse time of arrival (TOA), we have deduced the general form of test statistics in Fourier transform, and discussed their estimation performances. Meanwhile, a fast maximum likelihood (FML) technique is presented to estimate the pulse TOA, which outperforms cross correlation (CC) estimator and exhibits a performance comparable with maximum likelihood (ML) estimator in spite of a much less reduced computational complexity. Depending on the strategy of the difference minimum of pre-fit residuals, we present an effective forced phase-connected technique to achieve initial model parameters. Then, we use the observations with the Rossi X-Ray Timing Explorer (RXTE) and X-ray pulsar navigation-I (XPNAV-1) satellites for experimental studies, and discuss main differences for the root mean square (RMS) residuals calculated with the X-ray and radio ephemerides. Finally, a chi-square value (CSV) of pulse profiles is presented as a complementary indicator to the RMS residuals for evaluating the model parameters. The results show that the proposed timing solution is valid and effective, and the obtained model parameters can be a reasonable alternative to the radio ephemeris. Highlights: General form of test statistics is deduced in Fourier transform. Fast maximum likelihood technique is presented for pulse TOA estimation. Forced phase-connected method is presented on the residuals difference minimum. Long observation time leads to systematic errors in the model parameters.