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Paper: The Red Halos of Disk Galaxies
Volume: 396, Formation and Evolution of Galaxy Disks
Page: 229
Authors: Zackrisson, E.; Bergvall, N.; Flynn, C.; Caldwell, B.; Östlin, G.; Micheva, G.
Abstract: Deep optical/near-IR surface photometry of galaxies outside the Local Group have revealed the existence of faint and very red halos around objects as diverse as spirals and blue compact galaxies. The colors of these structures are much too extreme to be reconciled with resolved stellar populations like those seen in the halos of the Milky Way or M 31, and alternative explanations like dust reddening, high metallicities or nebular emission are also disfavored. A stellar population obeying an extremely bottom-heavy initial mass function, similar to that recently reported for the LMC field population, is on the other hand consistent with all available data. Because of its high mass-tolight ratio, such a population would effectively behave as baryonic dark matter and could account for some of the baryons still missing from local inventories. Here, we report on a number of recent developments in this field.
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