One important technique to understand the inner disc-corona geometry in accreting black hole systems is to measurement and model the Fourier frequency and energy-dependent X-ray reverberation delay spectra where the soft, reprocessed emission from the inner accretion disc is delayed with respect to the direct hard X-ray flashes from the corona. Such a modelling, based on simplified assumptions, allows us the first time to answer: 'What happens to disc corona geometric configuration when the primary X-ray flux changes?' In this talk, I will present results from the reverberation delay analysis of a variable, bright Seyfert 1 galaxy NGC 4593. Using the reverberation delay modelling technique on different observations where the X-ray flux changes by a factor of ~2-3, we observe that the model-predicted coronal size changes significantly. Such an effort will allow us to constrain the disc corona interactions as a response to the changing X-ray flux.

Location: Sporilov, mistnost 101