Fast variability as a probe of the smallest regions around accreting black holes
Fast variability as a probe of the smallest regions around accreting black holes
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DOI：
10.1093/mnras/stt315
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发表时间：
2013-01
影响因子：
4.8
通讯作者：
Magnus Axelsson;L. Hjalmarsdotter;C. Done
中科院分区：
文献类型：
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作者：
Magnus Axelsson;L. Hjalmarsdotter;C. Done
我们从黑洞XTE J1550-564中提取了从硬到软状态转变到爆发的最快变化（10 Hz以上）的光谱。我们证实了以前的结果，快速变化不包含显着的光盘组件，尽管这是强烈存在于软观测的总频谱。我们对电离反射的建模明显优于之前的工作，并表明与总发射相比，这在快速变率谱中也被抑制。这与快速变率起源于黑洞附近的热内流而不是吸积盘或其上方的日冕是一致的，然而，快速变率谱并不简单地与总康普顿化发射相同。它总是明显更硬，随着爆发期间光谱的软化而增加。这增加了时间滞后的证据，证明康普顿化区域是不均匀的，更硬的光谱产生最接近黑洞，同一区域产生最快的变化。
We extract the spectra of the fastest variability (above 10 Hz) from the black hole XTE J1550-564 during a transition from hard to soft state on the rise to outburst. We confirm previous results that the rapid variability contains no significant disc component despite this being strongly present in the total spectrum of the softer observations. We model ionized reflection significantly better than previous work, and show that this is also suppressed in the rapid variability spectrum compared to the total emission. This is consistent with the fast variability having its origin in a hot inner flow close to the black hole rather than in the accretion disc or in a corona above it. However, the rapid variability spectrum is not simply the same as the total Comptonized emission. It is always significantly harder, by an amount which increases as the spectrum softens during the outburst. This adds to evidence from time lags that the Comptonization region is inhomogeneous, with harder spectra produced closest to the black hole, the same region which produces the fastest variability.