The aim of this talk is to discuss the physical processing of cosmic dust under extreme conditions. In the first part of the talk, I will illustrate my research about Polycyclic Aromatic Hydrocarbons (PAHs). These molecules are an ubiquitous component of the Interstellar Medium, dominating the mid-infrared emission of many astronomical objects. However, very little was known about the destiny of PAHs when they are bombarded by high-velocity ions and electrons arising from shocks, hot gas and cosmic rays.
What happens to the PAH molecules under these extreme conditions? Will they be able to survive, maintaining their character, or will they be severely damaged or even completely destroyed? And what are the astrophysical implications of such processing ?
The second part of the talk will focus on the specific case of the destruction of newly formed dust grains by the reverse shock propagating into the supernova remnant Cassiopeia A. Theoretical models and recent observations indicate supernovae as important dust factories. However, the amount of fresh dust able to reach the interstellar medium, and contribute to the emission observed at all redshift, is not well determined. I will show how the destruction by the reverse shock could help clarifying this still-open problem, whose solution is crucial for understanding the origin and evolution of dust in the local and high-redshift universe .