Carbonaceous dust under extreme conditions

Elisabetta Micelotta

June 01, 2012

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Abstract: The aim of this talk is to discuss the physical processing of cosmic carbonaceous 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. While theoretical models indicate supernovae as main dust factories, the amount of fresh dust observed is still orders of magnitude lower than the predicted quantity. I will show how the destruction by the reverse shock could help clarifying this still-open problem.