Multi-timescale X-ray reverberation mapping of accreting black holes

Understand

Accreting black holes show characteristic reflection features in their X-ray spectrum, including an iron K$\alpha$ line, resulting from hard X-ray continuum photons illuminating the accretion disk.

• The reverberation lag resulting from the path length difference between direct and reflected emission provides a powerful tool to probe the innermost regions around both stellar-mass and supermassive black holes.
• Here, we present for the first time a reverberation mapping formalism that enables modeling of energy dependent time lags and variability amplitude for a wide range of variability timescales, taking the complete information of the cross-spectrum into account.
• We use a pivoting power-law model to account for the spectral variability of the continuum that dominates over the reverberation lags for longer time scale variability.