Piergiorgio Casella (INAF-Roma, Italy)

Beyond X-ray timing: fast multi-wavelength variability from the vicinity of compact objects

The study of X-ray variability in X-ray binaries has represented - and still is - one of the most powerful tools
to study the accretion flow in the vicinity of compact objects. A wealth of multi-wavelength campaigns during
the last decade has shown that significant emission at shorter wavelengths than X-rays can be detected from
the same inner regions studied through X-ray timing. At the same time, the advent of new instrumentation
has made possible to extend high time resolution astronomy to such wavelengths, in particular optical and
infrared. This is now opening new exciting windows, allowing the study of multi-wavelength fast variable
emission from X-ray binaries, and ultimately offering a more complete picture of what happens in the vicinity
of black holes and neutron stars. This field is at its dawn, but it is already showing its large potential. I will
quickly review the state of the art, and show how having an X-ray timing satellite flying in the near future will
be crucial to fully harness the great potential of these techniques.