PAHs and the Universe
Driven by ground-based, airborne, and IRAS observations, the PAH hypothesis was first formulated, some twenty five years ago: the wide spread mid-IR emission features in the 3-13 µm range are carried by large Polycyclic Aromatic Hydrocarbon molecules. These molecules are thought to be a ubiquitous component of the interstellar medium of galaxies, to play an important role in its physical and chemical characteristics, and form a key link between small hydrocarbon species and large carbonaceous grains.
Following the great advances driven by ground-based, ISO, Spitzer and AKARI observations and based upon extensive laboratory studies, we have now reached a stage where we can use these features as diagnostic tools to study star formation processes and protoplanetary disks. Indeed, PAHs and the IR emission features may provide much insight into star formation and galaxy assemblage in the early Universe.
We are entering the Herschel/Planck area that will open the possibility to better characterize the mid-IR carriers through their contribution to the far-IR and mm emissions. Increased performances in sensitivity and spatial resolution of the next generation of ground-based and space-based IR instruments are also anticipated. It is therefore a good time to discuss the state-of-the-art of the PAH hypothesis and to chart the future.
This symposium is aimed at bringing together experts in the area of astronomical observations, laboratory studies, and astronomical modeling of interstellar PAHs and related carbon dust populations. It is also a good occasion to celebrate the accomplishments of Alain Léger and Lou Allamandola in opening up and driving this field for many years.