New constraints on disk-dissipation processes from the relation between accretion and X-ray activity

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As discussed in the general introduction, Type I transition disks (TDs), which present small inner cavities and a depleted accretion signature, are thought to be objects caught in the act of dispersal. Photoevaporation from X-ray radiation from the central star is thought to be the main driver in the dispersal of disks around solar and later-type stars. We want to test models of X-ray driven disk photoevaporation leading to the formation of transition disks by using new observational data to study the relation between accretion rates of young stars and their X-ray emission. The aim is to combine the numerous available high-quality X-ray data of young stars in different regions with new and highly reliable accretion rates that can be derived from the new spectroscopic data on these stars. In this way, we will be able to study the relation between X-ray emission and accretion with much larger samples (hundreds of stars rather than just a few dozen) and for different regions spanning a range of ages, and to test the predictions of theoretical models of X-ray driven disk photoevaporation and the corresponding effects on the disk accretion rate. This is of fundamental importance to understand the formation and residual accretion rate distribution of transition disks.