XTE J1550-5642001年"迷你爆发"的X射线能谱研究

X-ray Energy Spectra Study of Mini-outburst of XTE J1550–564 in 2001

黑洞X射线暂现源的迷你爆发是一类峰值光度较低、持续时间较短的爆发.由于观测数据较少,其物理机制仍不清楚.利用RXTE(Rossi X-ray Timing Explorer)卫星从2001年1月28日到3月14日的数据,研究了黑洞X射线暂现源XTE J1550-5642001年迷你爆发的X射线能谱特性.发现在本次迷你爆发中,XTE J1550-564的X射线能谱可以用幂律谱很好地拟合.整个爆发的硬度强度图不是标准的q型,而是一直保持在最右侧.此外,还分析了此次爆发谱指数Γ与未吸收的2-10 keV能段的X射线流量F_(2-10) keV的相关性,发现Γ-F_(2-10) keV呈反相关关系,且谱指数Γ∈[1.35,1.72].上述结果表明2001年这次爆发一直处于低/硬态,它的X射线辐射主要来自于辐射低效的吸积模式,如ADAF(Advection-Dominated Accretion Flow).

The mini-outbursts of the black hole X-ray transients are a kind of outburst with low peak luminosity and short duration.Due to the lack of observational data,the physical mechanism is still unclear.Using data from RXTE(Rossi X-Ray Timing Explore)satellite from January 28 to March 14,2001,we studied the X-ray energy spectrum characteristics in the mini-outburst from X-ray transient XTE J1550-564 of the black hole.It was found that the X-ray energy spectrum of XTE J1550-564 in this mini-outburst could be well fitted with a power law spectrum.The evolution of the hardness-intensity diagram throughout the outburst is not a canonical“q-track pattern”,but lies on the far right.In addition,we also analyzed the correlation between X-ray photon indexΓand unabsorbed 2-10 keV X-ray flux F_(2-10) keV,and found that there is an anti-correlation betweenΓand F_(2-10) keV.Meanwhile,the photon indexΓis 1.35 to 1.72.Our results suggest that the outburst in 2001 has been in a low/hard state,its X-ray radiation mainly comes from the low-efficient accretion mode,such as ADAF(Advection-Dominated Accretion Flow).