Invited Talk

PAHs and the Interstellar Extinction Curve

¹Giacomo Mulas, ¹Silvia Casu, ¹Cesare Cecchi-Pestellini, ²Christine Joblin, ³Alberto Zonca (¹INAF - Osservatorio Astronomico di Cagliari, ²CNRS - Institut de Recherche en Astrophysique et Planétologie - UMR 5277, ³Dipartimento di Scienze Fisiche - Università di Cagliari)

Polycyclic Aromatic Hydrocarbons are nowadays commonly accepted to be one of the major components of the Interstellar Medium, and thereby to be an important contributor to Interstellar extinction. Their contribution can be represented either as a simplified, average model ("astronomical PAHs") or as a combination of real cross-sections. The former approach aims at simplicity, at the price of giving up most of the possibility to use the interstellar curve to constrain the properties of interstellar PAHs. The latter approach has the big disadvantage of using a necessarily (very) incomplete set of PAHs, subject to the availability of real cross-sections, and despite this of having a severely underconstrained problem (too many free parameters even with a mixture of few tens of PAHs). The contribution of PAHs to the extinction curve will be reviewed, and we will outline what physical information can be possibly reliably obtained by fitting a "real" PAH mixture to the Interstellar extinction curve.

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