Summary of the Meeting

This symposium has shown that the field of astrophysical PAHs remains extremely active and lively. Thanks to Spitzer Space Telescope, the number of PAH papers has spectacularly increased, including now up to the young Universe. Laboratory and theoretical works have progressed in proportion. Salient features of the six sessions of the symposium are briefly reviewed. Comprehensive analyses of the rich and complex infrared spectra of interstellar PAHs are now well established, based on a large database of observational data. PAHs are fully confirmed as excellent tracers of star formation, but their emission strongly depends on metallicity. Various observations, especially in harsh environments, have confirmed the complexity of the lifecycle of PAHs in space, and the need for multiple formation modes. Electronic properties remain a major issue for astronomical PAHs, including their possible connection with the diffuse interstellar bands, and the possible importance of protonated PAHs. Progress in studying complex carbonaceous compounds, such as those of various soots, and in synthesizing very large PAHs may give important clues for understanding interstellar PAHs. Significant progress was also reported in modeling the important role of PAHs in the physics and chemistry of the interstellar medium.