黑洞候选体X射线双星Cyg X-1硬度比周期特性研究

A Study on the Hardness Ratio Periodicity of the X-ray Binary Cyg X-1 as a Black Hole Candidate

利用离散傅里叶分析法,基于RXTE(Rossi X-ray Timing Explorer)/ASM(All-Sky Monitor,1.5～12 keV)观测数据,对黑洞候选体X射线双星Cyg X-1硬度比HR(5～12 keV/3～5 keV)(简写HR)的时变特性进行了分析,结果表明黑洞候选体X射线双星Cyg X-1硬度比HR存在明显的周期特性:(1)混合态(硬态+软态,本文指MJD=50087～55841期间所有的观测数据)时,HR存在T≈5.6 d、40.0 d、78.4 d、173.8 d以及400/800 d的时变周期;(2)硬态时,HR存在T≈5.6 d、33.7/67.6 d、45.3 d和165.3 d的周期特性;(3)软态时,HR出现了T≈38.5 d、48.1 d和128.3 d的周期性变化.并利用粘滞理论和Zdziarski吸积盘模型讨论了以上周期特性的物理机制.

Using the All-Sky Monitor （ASM, 1.5 - 12 keV） data of Rossi X-ray Timing Explorer （RXTE） from January 1996 to October 2011, we have analyzed in detail the power spectrum of the hardness ratio HR （5 - 12 keV/3 - 5 keV） of the X-ray binary Cyg X-1 as a black hole candidate. The results show that the hardness ratio exhibited the following periodic variations： （1） During MJD= 50087 ≈ 55841, the HR presented the periodicities of T ≈ 5.6 d, T ≈ 40.0 d, T ≈78.4 d, T ≈ 173.8 d, and T ≈400/800 d; （2） When Cyg X-1 was in the hard state, the HR presented the periodicities of T ≈ 5.6 d, T ≈ 33.7/67.6 d, T ≈ 45.3 d, and T ≈165.3 d; （3） When Cyg X-1 was in the soft state, the HR presented the periodicities of T ≈ 38.5 d, T≈ 48.1 d, and T ≈128.3 d. Moreover, using the viscosity theory and Zdziarski accretion disk model, we discuss the physical mechanism about the periodicities.