Université Paul Sabatier - Bat. 3R1b4 - 118 route de Narbonne 31062 Toulouse Cedex 09, France

Accueil > Événements > Séminaires 2014

Interstellar PAHs : a challenge for molecular physicists

Christine Joblin, IRAP, Université de Toulouse (UPS-OMP), CNRS

Polycyclic aromatic hydrocarbons (PAHs) have been proposed to be an ubiquitous component of cosmic matter. Interstellar PAHs absorb UV photons from stars and reemit the energy in the Aromatic Infrared Bands (AIBs). They play a key role in the heating of the gas by photoelectric effect, the ionisation balance and the chemistry. The big questions which need to be addressed are :
- (i)- What can we learn on this PAH population from the analysis of the AIB spectrum ?,
- (ii)- how are cosmic PAHs formed and how do they evolve ?,
- (iii)- what is their impact on the physics and chemistry of astrophysical environments ?

Over the years, research on this topic has fostered interesting developments in molecular physics, like the detailed study of the impact of anharmonicity on the IR emission features, that of relaxation pathways in energized PAHs on the survival of these species, or the study of the properties of related systems such as PAH clusters or PAH-metal complexes.

In my seminar, I will describe how this research has progressed thanks to a synergy between laboratory astrophysicists and molecular physicists. The PAH photophysics/chemistry in space enables to probe molecular processes in conditions of extreme isolation from the environment that are otherwise difficult to study. This led to the development of dedicated laboratory setups and theoretical simulations at the forefront of molecular physics. I will illustrate the point on a few examples and will briefly describe the perspectives given by the starting ERC Synergy project Nanocosmos.