Correlated fast X-ray and optical variability in the black-hole candidate XTE J1118+480
Correlated fast X-ray and optical variability in the black-hole candidate XTE J1118+480
复制标题
DOI：
10.1038/35102515
复制
发表时间：
2001-11
期刊：
影响因子：
64.8
通讯作者：
G. Kanbach;C. Straubmeier;H. Spruit;T. Belloni
中科院分区：
文献类型：
--
作者：
G. Kanbach;C. Straubmeier;H. Spruit;T. Belloni
黑洞在吸积气体时变得可见，气体的一个常见来源是亲密的恒星伴星。这一过程的标准理论(称为“薄吸积盘”)不能解释与这些系统相关的一些壮观现象，例如它们的X射线变异性和相对论外流，这表明对实际物理条件缺乏了解。在多个波长的同时观测可以对这些条件提供很强的约束。在这里，我们报告了对第二个瞬变源XTE J1118+480的同时高时间分辨率X射线和光学观测，这些观测显示了辐射之间强烈但令人费解的相关性。随着X射线输出的增加，光发射突然增加，但比X射线提前2-5秒下降。这一结果在最简单的光学发射模型中并不容易理解，在这种模型中，光来自再处理的X射线。这可能与早先提出的光学光是回旋同步辐射的说法更一致，该辐射起源于距离黑洞约20,000 公里的区域。我们认为，时间依赖性是相对缓慢的(<；0.1c)，磁控外流的证据。
Black holes become visible when they accrete gas, a common source of which is a close stellar companion. The standard theory for this process (invoking a ‘thin accretion disk’) does not explain some spectacular phenomena associated with these systems, such as their X-ray variability and relativistic outflows, indicating some lack of understanding of the actual physical conditions. Simultaneous observations at multiple wavelengths can provide strong constraints on these conditions. Here we report simultaneous high-time-resolution X-ray and optical observations of the transient source XTE J1118+480, which show a strong but puzzling correlation between the emissions. The optical emission rises suddenly following an increase in the X-ray output, but with a dip 2–5 seconds in advance of the X-rays. This result is not easy to understand within the simplest model of the optical emission, where the light comes from reprocessed X-rays. It is probably more consistent with an earlier suggestion that the optical light is cyclosynchrotron emission that originates in a region about 20,000 km from the black hole. We propose that the time dependence is evidence for a relatively slow (<0.1c), magnetically controlled outflow.