Speaker
Description
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 stellarmass 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.