Mid-Infrared Galaxy Classification Based on Silicate Obscuration and PAH Equivalent Width

We present a new diagnostic diagram for mid-infrared spectra of infrared galaxies based on the equivalent width of the 6.2mm PAH emission feature and the strength of the 9.7 mm silicate feature. Based on the positions in this diagram, we classify galaxies into nine classes ranging from continuum-dominated AGN hot dust spectra and PAHdominated starburst… (More)