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Mid Infrared Properties of Low Metallicity Blue Compact Dwarf Galaxies From Spitzer/IRS

Yanling Wu·V. Charmandaris·Lei Hao·B. R. Brandl·J. Bernard-Salas·H. W. W. Spoon·J. R. Houck
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Abstract

We present a {\em Spitzer}-based mid-infrared study of a large sample of Blue Compact Dwarf galaxies (BCD) using the Infrared Spectrograph (IRS), including the first mid-IR spectrum of IZw18, the archetype for the BCD class and among the most metal poor galaxies known. We show the spectra of Polycyclic Aromatic Hydrocarbon (PAH) emission in low-metallicity environment. We find that the equivalent widths (EW) of PAHs at 6.2, 7.7, 8.6 and 11.2 $μ$m are generally weaker in BCDs than in typical starburst galaxies and that the fine structure line ratio, [NeIII]/[NeII], has a weak anti-correlation with the PAH EW. A much stronger anti-correlation is shown between the PAH EW and the product of the [NeIII]/[NeII] ratio and the UV luminosity density divided by the metallicity. We conclude that PAH EW in metal-poor high-excitation environments is determined by a combination of PAH formation and destruction effects.

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Yanling Wu, V. Charmandaris, Lei Hao, B. R. Brandl, J. Bernard-Salas, H. W. W. Spoon, J. R. Houck. 2005-10-31. Mid Infrared Properties of Low Metallicity Blue Compact Dwarf Galaxies From Spitzer/IRS. https://doi.org/10.1086/499226

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