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Relating spatially resolved optical attenuation, dust, and gas in nearby galaxies
In this study, we investigate the correlation among dust surface density (Σdust), surface density of all gas components (ΣHI, ΣH2, Σgas) and optical attenuation derived independently from Balmer decrement (AV,BD) and SED fitting (AV,SED), at a spatial resolution lower than 0.5kpc. We investigate all nearby spiral galaxies with atomic and molecular gas maps, MUSE integral-field spectra and dust emission data.
Maps of observed and derived properties of NGC4321, one of the five galaxies in the sample. Grey points correspond to rejected pixels and smaller coloured points indicate pixels beyond the area that the SED-fitting was performed. Contours are taken from log Σdust maps.
We find that Σdust traces better the molecular and total gas content, rather than atomic gas. The correlations of Σdust with ΣH2 and Σgas hold both for individual galaxies and for the whole sample. The same is also found for the correlations of AV,BD with the gas components (see Fig. 5 in the paper for more details)
To investigate the correlation between the dust emission and the optical attenuation, we performed a full radiative transfer calculation assuming different dust-stars geometries (screen, slab, sandwich). Both AVBD and AVSEDyoung against Σdust suggest the combination of a screen dust component and a mixed dust and emitting material configuration. On the contrary, AVSEDold as a function of the Σdust follows the models where sources and dust are mixed.
The AVBD and the AVSEDyoung are in a very good agreement, with 88.6% of our data points differing by less than 0.5dex. SED-fitting derived AVSEDyoung could serve as a tracer of the attenuation in larger samples, where IFU observations might be more challenging.
You can find more of this work at the corresponding article published on the Astronomy & Astrophysics Journal:
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