Astronomy and Astrophysics – Astrophysics
Scientific paper
2008-02-16
Proceedings of the Fourth Spitzer Conference: "The Evolving ISM in the Milky Way and Nearby Galaxies", held in Pasadena dec. 2
Astronomy and Astrophysics
Astrophysics
14 pages, 16 color figures
Scientific paper
In the present contribution, I summarize a systematic study of ISO and Spitzer mid-IR spectra of Galactic regions and star forming galaxies. This study quantifies the relative variations of the main aromatic features inside spatially resolved objects as well as among the integrated spectra of 50 objects. Our analysis implies that the properties of the PAHs are remarkably universal throughout our sample and at different spatial scales. In addition, the relative variations of the band ratios, as large as one order of magnitude, are mainly controled by the fraction of ionized PAHs. In particular, I show that we can rule out both the modification of the PAH size distribution and the mid-IR extinction, as an explanation of these variations. High values of the I(6.2)/I(11.3) ratio are found to be associated with the far-UV illuminated surface of PDRs, at the scale of an interstellar cloud, and associated with star formation activity, at the scale of a galaxy. Using a few well-studied Galactic regions, we provide an empirical relation between the I(6.2)/I(11.3) ratio and the ionization/recombination ratio G0/ne. Finally, I show that these trends are consistent with the detailed modeling of the PAH emission within photodissociation regions, taking into account the radiative transfer, the stochastic heating and the charge exchange between gas and dust.
No associations
LandOfFree
A Multiscale Study of Polycyclic Aromatic Hydrocarbon Properties in Galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A Multiscale Study of Polycyclic Aromatic Hydrocarbon Properties in Galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Multiscale Study of Polycyclic Aromatic Hydrocarbon Properties in Galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-248287