论文标题
黑洞二进制V404 CYG的快速光谱过渡
Rapid spectral transition of the black hole binary V404 Cyg
论文作者
论文摘要
在2015年6月的黑洞二进制V404 CYG的爆发中，X射线亮度和光谱的快速变化很常见。整体监控活动检测到了壮观的爱丁顿有限的X射线耀斑，但在较低的通量水平上也很快变化。 2015年6月21日，20小时50分钟，3-10 KEV JEM-X数据以及同时的光学数据开始显示这些低频率状态之一的逐渐变亮。 15分钟后，仅15 s的20-40 KEV IBIS/ISGRI光曲线中通量的速度增加。转变前和后期光谱的最佳拟合模型需要部分覆盖吸收剂。吸收器参数保持恒定，但是在事件期间，光谱斜率显着变化，光子指数从$γ\ \ $γ\ $γ\约2.3 $降低。我们建议，快速的20-40 keV通量增加是由光谱状态转变引起的，该光谱状态过渡是从我们的直接视图中隐藏的，或者突然减少了磁盘流出中主要X射线发射的compton下散射量。
During the June 2015 outburst of the black hole binary V404 Cyg, rapid changes in the X-ray brightness and spectra were common. The INTEGRAL monitoring campaign detected spectacular Eddington-limited X-ray flares, but also rapid variations at much lower flux levels. On 2015 June 21 at 20 h 50 min, the 3-10 keV JEM-X data as well as simultaneous optical data started to display a gradual brightening from one of these low-flux states. This was followed 15 min later by an order-of-magnitude increase of flux in the 20-40 keV IBIS/ISGRI light curve in just 15 s. The best-fitting model for both the pre- and post-transition spectra required a Compton-thick partially covering absorber. The absorber parameters remained constant, but the spectral slope varied significantly during the event, with the photon index decreasing from $Γ\approx 3.7$ to $Γ\approx 2.3$. We propose that the rapid 20-40 keV flux increase was either caused by a spectral state transition that was hidden from our direct view, or that there was a sudden reduction in the amount of Compton down-scattering of the primary X-ray emission in the disk outflow.
