Reverberation reveals the truncated disc in the hard state of GX 339-4
Reverberation reveals the truncated disc in the hard state of GX 339-4
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DOI：
10.1093/mnras/stz933
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发表时间：
2018-11
影响因子：
4.8
通讯作者：
Ra’ad D Mahmoud;C. Done;B. De Marco-B.-De Marco-2124187063
中科院分区：
文献类型：
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作者：
Ra’ad D Mahmoud;C. Done;B. De Marco-B.-De Marco-2124187063
黑洞双星中硬态的性质和几何形状是有争议的。宽带连续谱和快速变化特性可以在内盘蒸发成几何厚度热流的模型中得到解释。然而，这些模型受到了持续探测到一条极宽的铁线的挑战，这要求圆盘向下延伸到高自旋黑洞的最后一个稳定轨道。如果康普顿化连续谱是多组分的而不是单一温度的，那么这个线宽可以大大减小，但是这样的模型是高度简并的。在这里，我们展示了一个特定的模型的径向分层连续耦合到一个模型的传播波动，适合一些最好的硬态数据从GX 339-4。这种全谱定时模型可以拟合时间平均谱、不同能量带中的功率谱以及这些带之间的频率相关滞后。对于第一次，我们还包括光盘混响，并表明，这个相同的频谱定时成功地预测所有时间尺度上的滞后能量谱。这给出了一种更鲁棒的方法来确定盘的内半径，该内半径为20 Rg的量级，即被显著截断。这开辟了一条道路，使用快速变化的光谱定时数据跟踪源的黑洞双星的几何形状在所有的状态。
The nature and geometry of the hard state in black hole binaries is controversial. The broadband continuum spectrum and fast variability properties can be explained in a model where the inner disc evaporates into a geometrically thick, hot flow. However these models are challenged by the persistent detection of an extremely broad iron line, which requires that the disc extends down to the last stable orbit of a high spin black hole. This line width can be considerably reduced if the Comptonisation continuum is multi-component rather than single temperature, but such models are highly degenerate. Here we show a specific model of a radially stratified continuum coupled to a model of propagating fluctuations, fit to some of the best hard state data from GX 339-4. This full spectral-timing model can fit the time averaged spectrum, the power spectra in different energy bands, and the frequency dependent lags between these bands. For the first time we also include disc reverberation and show that this same spectral-timing successfully predicts the lag-energy spectra on all timescales. This gives a more robust method to determine the inner radius of the disc, which is of order 20 Rg, i.e. significantly truncated. This opens up the way to use the fast variability spectral-timing data to trace the source geometry of black hole binaries in all states.