Polycyclic aromatic hydrocarbons in the dwarf galaxy IC 10

TL;DR

This study uses infrared data from the Spitzer Space Telescope to analyze the distribution and abundance of polycyclic aromatic hydrocarbons (PAHs) in the dwarf galaxy IC 10, revealing their non-uniform distribution and potential formation in dense gas regions.

Contribution

It provides new insights into the spatial distribution of PAHs in IC 10 and their relation to gas and star-forming regions, highlighting the impact of metallicity on PAH abundance.

Findings

PAHs constitute up to 4% of total dust mass in IC 10.

PAHs avoid bright HII regions and correlate with atomic and molecular gas.

No conclusive evidence of shock destruction of PAHs in IC 10.

Abstract

Infrared observations from the Spitzer Space Telescope archive are used to study the dust component of the interstellar medium in the IC~10 irregular galaxy. Dust distribution in the galaxy is compared to the distributions of H$\alpha$ and [SII] emission, neutral hydrogen and CO clouds, and ionizing radiation sources. The distribution of polycyclic aromatic hydrocarbons (PAH) in the galaxy is shown to be highly non-uniform with the mass fraction of these particles in the total dust mass reaching 4%. PAHs tend to avoid bright HII regions and correlate well with atomic and molecular gas. This pattern suggests that PAHs form in the dense interstellar gas. We propose that the significant decrease of the PAH abundance at low metallicity is observed not only globally (at the level of entire galaxies), but also locally (at least, at the level of individual HII regions). We compare the distribution of the PAH mass fraction to the distribution of high-velocity features, that we have detected earlier in wings of H$\alpha$ and SII lines, over the entire available galaxy area. No conclusive evidence for shock destruction of PAHs in the IC~10 galaxy could be found.