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Paper: The PAH Emission Deficit In Low-Metallicity Galaxies – A Spitzer View
Volume: 381, The Second Annual Spitzer Science Center Conference: Infrared Diagnostics of Galaxy Evolution
Page: 30
Authors: O’Halloran, B.; Satyapal, S.; Dudik, R.P.
Abstract: Archival observations of 18 starburst galaxies that span a wide range in metallicity reveal for the first time a correlation between the ratio of emission line fluxes of [FeII] at 26 μm and [NeII] at 12.8 μm and the 7.7 μm PAH strength, with the [FeII]/[NeII] flux ratio decreasing with increasing PAH strength. We also find a strong correlation between the [FeII]/[NeII] flux ratio and the host galaxy metallicity, with the flux ratio decreasing with increasing metallicity. Since [FeII] emission has been linked primarily to supernova shocks, we attribute the high [FeII]/[NeII] ratios in low-metallicity galaxies to enhanced supernova activity. We consider this to be a dominant mechanism for PAH destruction, rather than grain destruction in photo-ionized regions surrounding young massive stars. We also consider whether the extreme youth of the lowmetallicity galaxies is responsible for the lack of PAH emission.
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