2006/06/09 by E. Zackrisson, N. Bergvall, G. Ostlin +2
Physics and Astronomy · #Astronomy and Astrophysical Research #Dark matter halo #Galactic halo #Galaxies: Formation, Evolution, Phenomena #Galaxy #Halo #Milky Way #Population #Stellar mass #Stellar population #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/506928
published as Astrophys.J.650:812-817,2006 · 6 pages, 3 figures, Accepted for publication in ApJ
arxiv created 2006/06/09 · openalex publication_date 2006/10/18 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
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.