Prof. Tomaso Belloni

The first evidences of aperiodic variability from accreting X-ray sources comes from 1972, almost half a century ago. The big advancements in the field have been possible by a number of X-ray missionas, the most important being RossiXTE. While fast aperioodic variability has been largely ignored by most scientists in the past, it is now clear that even spectral studies must take into account time variations. I will go through the main historical points in the field and connect them to the current situation. At present, we have three missions that are bringing forth the heritage of RossiXTE: NICER, Astrosat and HXMT, which are going to open the road to future ones like eXTP.