An application of Hilbert-Huang transform on the non-stationary astronomical time series: The superorbital modulation of SMC X-1

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Title:	An application of Hilbert-Huang transform on the non-stationary astronomical time series: The superorbital modulation of SMC X-1
Authors:	吳明佳;Hu, Chin-Ping;Chou, Yi;Wu, Ming-Chya;Yang, Ting-Chang;Su, Yi-Hao
Contributors:	理學院物理學系
Keywords:	Hilbert-Huang transform;like the dynamic power spectrum (Clarkson et al. 2003) and the slide Lomb-Scargle periodogram (Trowbridge et al. 2007);SMC X-1;SMC X-1 1. INTRODUCTION The high-mass X-ray binary SMC X-1 consists of a 1.06 M⊙ neutron star (van der Meer et al. 2007) and a 17.2 M⊙ supergiant (Reynolds et al. 1993). The orbital period of this system is 3.89 d obtained from the X-ray eclipse. Gruber & Rothschild found that the SMC X-1 exhibits an X-ray periodicity with a rough time scale of 60 d. This periodicity was then confirmed by Wojdowski et al. and the cycle lengths were reported to vary with time. The behavior of the period variation was investigated after several timefrequency analysis techniques;superorbital modulations;were applied on the All-Sky Monitor (ASM) light curve. We present our analysis by;X-ray binaries;천문학
Date:	2013-01-01
Issue Date:	2026-04-23 11:42:18 (UTC+8)
Publisher:	The Korean Space Science Society;한국우주과학회
Abstract:	摘要： We present the Hilbert-Huang transform (HHT) analysis on the quasi-periodic modulation of SMC X-1. SMC X-1, consistingof a neutron star and a massive companion, exhibits superorbital modulation with a period varying between ~40 d and ~65 d.We applied the HHT on the light curve observed by the All-Sky Monitor onboard Rossi X-ray Timing Explorer (RXTE) to obtainthe instantaneous frequency of the superorbital modulation of SMC X-1. The resultant Hilbert spectrum is consistent with thedynamic power spectrum while it shows more detailed information in both the time and frequency domains. According to theinstantaneous frequency, we found a correlation between the superorbital period and the modulation amplitude. Combiningthe spectral observation made by the Proportional Counter Array onboard RXTE and the superorbital phase derived in theHHT, we performed a superorbital phase-resolved spectral analysis of SMC X-1. An analysis of the spectral parameters versusthe orbital phase for different superorbital states revealed that the diversity of nH has an orbital dependence. Furthermore,we obtained the variation in the eclipse profiles by folding the All Sky Monitor light curve with orbital period for differentsuperorbital states. A dip feature, similar to the pre-eclipse dip of Her X-1, can be observed only in the superorbital ascendingand descending states, while the width is anti-correlated with the X-ray flux. 出版者： 한국우주과학회 出版日期： 2013-06-01 出處： Journal of Astronomy and Space Sciences, 2013, 30(2), , pp.79-82 資源來源： DOAJ Directory of Open Access Journals 識別號： ISSN: 2093-5587 識別號： ISSN: 2093-1409 識別號： EISSN: 2093-1409 識別號： DOI: 10.5140/JASS.2013.30.2.079
Appears in Collections:	[Department of Physics] journal & Dissertation

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