A Relationship of Polycyclic Aromatic Hydrocarbon Features with Galaxy Merger in Star-forming Galaxies at $z<0.2$

Abstract

Using the AKARI, Wide-field Infrared Survey Explorer (WISE), Infrared Astronomical Satellite (IRAS), Sloan Digital Sky Survey (SDSS) and Hubble Space Telescope (HST) data, we investigated the relation of polycyclic aromatic hydrocarbon (PAH) mass ($M_{\mathrm{PAH}}$), very small grain mass ($M_{\mathrm{VSG}}$), big grain mass ($M_{\mathrm{BG}}$) and stellar mass ($M_{\mathrm{star}}$) with galaxy merger for 55 star-forming galaxies at redshift $z<0.2$. Using the SDSS image at $z<0.1$ and the HST image at $z>0.1$, we divided the galaxies into merger galaxies and non-merger galaxies with the morphological parameter asymmetry $A$, and quantified merging stages of galaxies based on the morphological indicators, the second-order momentum of the brightest 20$\%$ region $M_{20}$ and the Gini coefficient. We find that $M_{\mathrm{PAH}}/M_{\mathrm{BG}}$ of merger galaxies tend to be lower than that of non-merger galaxies and there are no systematic differences of $M_{\mathrm{VSG}}/M_{\mathrm{BG}}$ and $M_{\mathrm{BG}}/M_{\mathrm{star}}$ between merger galaxies and non-merger galaxies. We find that galaxies with very low $M_{\mathrm{PAH}}/M_{\mathrm{BG}}$ seem to be merger galaxies at late stages. These results suggest that PAHs are partly destroyed at late stages of merging processes. Furthermore, we investigated $M_{\mathrm{PAH}}/M_{\mathrm{BG}}$ variations in radiation field intensity strength $G_0$ and the emission line ratio of $[\mathrm{O}\mathrm{I}]\lambda 6300/\mathrm{H}\alpha$ which is a shock tracer for merger galaxies and find that $M_{\mathrm{PAH}}/M_{\mathrm{BG}}$ decreases with increasing both $G_0$ and $[\mathrm{O}\mathrm{I}]/\mathrm{H}\alpha$. PAH destruction is likely to be caused by two processes; strong radiation fields and large-scale shocks during merging processes of galaxies.

14 pages, 13 figures, Accepted for publication in MNRAS

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Cited by in corpus (3)

• Metallicity-PAH Relation of MIR-selected Star-forming Galaxies in AKARI North Ecliptic Pole-wide Survey
• Processing of hydrocarbon dust in star-forming galaxies revealed with AKARI
• FASHI: A search for extragalactic OH megamasers with FAST