Slowly solving a 40 year old mystery in black hole variability

Almost since the discovery of the first confirmed accreting black holes in X-ray binary systems, we have known that their X-ray emission varies rapidly and that the variations seen in higher energy X-rays lag behind the variations seen in lower-energy X-rays. The origin of these so-called 'hard lags' has been a mystery for 4 decades, partly because they seem to be linked to the equally mysterious black hole 'corona', whose structure and origin is still hotly debated. Recently, we think we have managed to solve the mystery of the hard lags and thereby cast light on the nature of the corona. In my talk, as well as explaining the science I will use this mystery of black holes as an example of how many open scientific questions evolve only gradually, as our understanding of the wider picture also evolves, and that often the answers are staring us in the face. The big, breakthrough discoveries that grab the media spotlight, though important, are usually only a small part of the scientific process. The gradual evolution in our thinking is just as important for solving long-standing problems

Phil Uttley — API -- UvA
Thursday 23 March 2017, 12:00
Location: C4.174