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摘要
We model the infrared to submillimetre spectral energy distribution of 11 nearby galaxies of the Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel sample using Spitzer and Herschel data and compare model extrapolations at 870 mu m (using different fitting techniques) with Large APEX BOlometer CAmera (LABOCA) 870 mu m observations. We investigate how the differences between predictions and observations vary with model assumptions or environment. At global scales, we find that modified blackbody models using realistic cold emissivity indices (beta(c) = 2 or 1.5) are able to reproduce the 870 mu m observed emission within the uncertainties for most of the sample. Low values (beta(c) %26lt; 1.3) would be required in NGC 0337, NGC 1512 and NGC 7793. At local scales, we observe a systematic 870 mu m excess when using beta(c) = 2.0. The beta(c) = 1.5 or the Draine %26 Li (2007) models can reconcile predictions with observations in part of the discs. Some of the remaining %26apos;excesses%26apos; occur towards the centres and can be partly or fully accounted for by non-dust contributions such as CO(3-2) or, to a lesser extent, free-free or synchrotron emission. In three non-barred galaxies, the remaining excesses rather occur in the disc outskirts. This could be a sign of a flattening of the submm slope (and decrease of the effective emissivity index) with radius in these objects.
- 出版日期2014-4
