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Paper: Common Far-Infrared Properties of the Galactic Disk and Nearby Galaxies
Volume: 396, Formation and Evolution of Galaxy Disks
Page: 71
Authors: Hirashita, H.; Hibi, Y.; Shibai, H.
Abstract: A recent data analysis of the DIRBE far-infrared (FIR) map of the Galaxy and the Magellanic Clouds has shown that there is a tight correlation between the 60 μm−100 μm and 100 μm−140 μm colors. This FIR color relation called ‘main correlation’ can be interpreted as indicative of a sequence of various interstellar radiation fields with a common FIR optical property of grains. Here, we constrain the FIR optical properties of grains by comparing the calculated FIR colors with the observational main correlation. We show that if the emissivity index at 100 μm ≤ λ ≤ 200 μm is assumed to be ∼ 1–1.5 (not ∼ 2 as standard silicate or graphite), the main correlation can be successfully explained. Thus, we propose that the FIR emissivity index is ∼ 1–1.5 for the dust in the Galaxy and the Magellanic Clouds at 100 μm ≤λ ≤ 200 μm. We also find that the main correlation explains the FIR colors of nearby galaxies.
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