Aromatic Features in M101 HII Regions and Starburst Galaxies
Abstract
The behavior of the aromatic features as a function of metallicity/radiation field hardness in M101 HII regions and starburst galaxies is investigated using Spitzer/IRS spectra. These spectra reveal that the 6.2, 7.8+8.6, and 11.3 micron aromatics have different dependencies on metallicity/radiation field hardness. Specifically, the 6.2 and 7.8+8.6 micron aromatics are weak or absent at a metallicity, 12+log(O/H), of approx. 8.0 while the 11.3 micron feature remains relatively strong. These results apply to both the M101 HII regions and starbursts showing that HII regions can indeed be thought of as ``mini-starbursts.'' Comparison of this work with various candidate materials results in a good match with the annealing behavior in Quenched Carbonaceous Composite (QCC) which is an amorphous, hydrogenated, carbonaceous solid.
Keywords
Cite
@article{arxiv.astro-ph/0605544,
title = {Aromatic Features in M101 HII Regions and Starburst Galaxies},
author = {Karl D. Gordon and C. W. Engelbracht and J. -D. T. Smith and G. H. Rieke and K. A. Misselt},
journal= {arXiv preprint arXiv:astro-ph/0605544},
year = {2007}
}
Comments
6 pages, To appear in the proceedings for the Spitzer Science Center 2005 Conference: Infrared Diagnostics of Galaxy Evolution, Ed. R. Chary. November, 2005, Pasadena