J. R. Gerke, C. S. Kochanek
We measure the integrated contributions of dusty AGB stars and other luminous red sources to the mid-IR luminosities of 6 galaxies (M81, NGC 2403, NGC 300, M33 and the Magellanic Clouds). We find the dusty AGB stars contribute from 0.6% (M81) to 5.6% (SMC) of the 3.6 micron flux and 1.0% (M81) to 10.1% (SMC) of the 4.5 micron flux. We find a trend of decreasing AGB contribution with increasing galaxy metallicity, luminosity and mass and decreasing SSRF. However, these galaxy properties are strongly correlated in our sample and the most likely explanation of the trend is galaxy metallicity. The bright, red sources represent a smaller fraction of the luminosity, ~1.2% at 3.6 microns, however their dust is likely cooler and their contributions are likely larger at longer wavelengths. Excluding the SMC, the contribution from these sources correlates with the specific star formation rate as we would expect for massive stars. In total, after correcting for dust emission at other wavelengths, the dust around AGB stars radiates 0.1-0.8% of the bolometric luminosities of the galaxies. Thus, hot dust emission from AGB and other luminous dusty stars represent a small fraction of the total luminosities of the galaxies but a significant fraction of their mid-IR emissions.
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http://arxiv.org/abs/1207.7080
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