The remarkable rapid X-ray, ultraviolet, optical and infrared variability in the black hole XTE J1118+480
The remarkable rapid X-ray, ultraviolet, optical and infrared variability in the black hole XTE J1118+480
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黑洞 XTE J1118 480 中 X 射线、紫外线、光学和红外线的显着快速变化
DOI：
10.1046/j.1365-8711.2003.06938.x
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发表时间：
2003
影响因子：
4.8
通讯作者：
K. Horne
中科院分区：
文献类型：
--
作者：
R. Hynes;R. Hynes;C. Haswell;W. Cui;C. Shrader;K. O’Brien;K. O’Brien;S. Chaty;S. Chaty;S. Chaty;D. Skillman;J. Patterson;K. Horne
瞬变黑洞双星XTE J1118+480在所有波长都表现出惊人的快速变化，这在2000年4月至7月爆发期间得到了适当的观测。我们研究了跨越爆发平台期的时间分辨X射线、紫外线、光学和红外数据。我们发现，X射线和红外波段都表现出很大的变幅。紫外线和光学的可变性较弱，但与X射线中的可变性明显相关。至少，紫外线似乎是由连续体主导的，尽管谱线也是不同的。以X射线变化为参照点，我们发现长波紫外光的变化比短波紫外光的变化要晚。然而，哈勃太空望远镜计时的不确定性阻碍了对X射线绝对滞后的确定。传递函数显然不是增量函数，表现出显著的可重复结构。对于主信号，我们可以排除伴星再处理的来源--考虑到相对较高的轨道倾角，滞后信号的缺乏与此不一致。来自圆盘和/或伴星的弱再处理可能存在，但不是必需的，并且另一个分量必须主导变化。这可能是与X射线可变性相关的可变同步辐射，与我们早先对红外(IR)通量的解释一致，认为这是由于同步辐射而不是热盘发射。事实上，从红外到X射线的变化的宽带能量分布与光学薄同步辐射的预期是一致的。我们还跟踪了X射线、紫外光和光学中低频准周期振荡的演化。它在所有波长的性质都是相似的，这表明它是一个共同的起源。
The transient black-hole binary XTE J1118+480 exhibited dramatic rapid variability at all wavelengths which were suitably observed during its 2000 April–July outburst. We examine time-resolved X-ray, ultraviolet, optical and infrared data spanning the plateau phase of the outburst. We find that both X-ray and infrared bands show large amplitude variability. The ultraviolet and optical variability is more subdued, but clearly correlated with that seen in the X-rays. The ultraviolet, at least, appears to be dominated by the continuum, although the lines are also variable. Using the X-ray variations as a reference point, we find that the ultraviolet (UV) variability at long wavelengths occurs later than that at short wavelengths. Uncertainty in the Hubble Space Telescope timing prohibits a determination of the absolute lag with respect to the X-rays, however. The transfer function is clearly not a delta-function, exhibiting significant repeatable structure. For the main signal we can rule out an origin in reprocessing on the companion star – the lack of variation in the lags is not consistent with this, given a relatively high orbital inclination. Weak reprocessing from the disc and/or companion star may be present, but is not required, and another component must dominate the variability. This could be variable synchrotron emission correlated with X-ray variability, consistent with our earlier interpretation of the infrared (IR) flux as due to synchrotron emission rather than thermal disc emission. In fact, the broad-band energy distribution of the variability from IR to X-rays is consistent with expectations of optically thin synchrotron emission. We also follow the evolution of the low-frequency quasi-periodic oscillation in X-rays, UV, and optical. Its properties at all wavelengths are similar, indicating a common origin.