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Updated: Feb 19, 2026

Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic
Published on: August 25, 2016
Reverberation lags viewed in hard X-rays from an accreting stellar-mass black hole
Bei You1, Wei Yu2,3, Adam Ingram4
1Department of Astronomy, School of Physics and Technology, Wuhan University, Wuhan, China. youbei@whu.edu.cn.
None:
The X-ray-emitting corona near a black hole (BH) is too small to be directly imaged, but the rapid variability is used to infer the geometry by measuring time lags caused by coronal X-rays reflecting off the disk, known as reverberation lags. Though reverberation lags have previously been detected for some supermassive BHs in active galactic nuclei (AGNs), detecting them from stellar-mass BHs poses much greater challenges due to their size being over a million times smaller. Previous measurements of reverberation lags for stellar-mass BHs were limited to energies below 10 keV. Here, we report the detection of the Compton hump reverberation, peaking at about 30 keV, from an X-ray binary. The accompanying detection of an iron line feature at about 6.4 keV confirms the X-ray reverberation scenario and provides strong evidence that accretion flows in AGNs and X-ray binaries are governed by an ubiquitous process.
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