The Red Halo Phenomenon
2006 (English)In: The Astrophysical Journal, ISSN 0004-637X, Vol. 650, no 2, 812-817 p.Article in journal (Refereed) Published
Optical and near-IR observations of the halos of disk galaxies and blue compact galaxies have revealed a very red spectral energy distribution that cannot easily be reconciled with a normal, metal-poor stellar population such as that in the stellar halo of the Milky Way. Here spectral evolutionary models are used to explore the consequences of these observations. We demonstrate that a stellar population of low to intermediate metallicity but with an extremely bottom-heavy initial mass function can explain the red halos around both types of objects. Other previously suggested explanations, such as nebular emission or very metal-rich stars, are shown to fail in this respect. This indicates that if the reported halo colors are correct, halo populations dominated by low-mass stars may be a phenomenon common to galaxies of very different Hubble types. Potential tests of this hypothesis are discussed, along with its implications for the baryonic dark matter content of galaxies.
Place, publisher, year, edition, pages
2006. Vol. 650, no 2, 812-817 p.
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:su:diva-20148DOI: doi:10.1086/506928OAI: oai:DiVA.org:su-20148DiVA: diva2:186673