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Dependence of the local reionization history on halo mass and environment: did Virgo reionize the Local Group?

Weinmann, Simone M. ; Macciò, Andrea V. ; Iliev, Ilian T. ; Mellema, Garrelt ; Moore, Ben

In: Monthly Notices of the Royal Astronomical Society, 2007, vol. 381, no. 1, p. 367-376

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    Titre
    • Dependence of the local reionization history on halo mass and environment: did Virgo reionize the Local Group?
    Auteur
    • Weinmann, Simone M.. Institute for Theoretical Physics, University of Zurich, CH-8057 Zurich, Switzerland
    • Macciò, Andrea V.. Institute for Theoretical Physics, University of Zurich, CH-8057 Zurich, Switzerland
    • Iliev, Ilian T.. Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St George Street, Toronto, ON, Canada M5S 3H8
    • Mellema, Garrelt. Stockholm Observatory, AlbaNova University Centre, Stockholm University, SE-106 91 Stockholm, Sweden
    • Moore, Ben. Institute for Theoretical Physics, University of Zurich, CH-8057 Zurich, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Monthly Notices of the Royal Astronomical Society, 2007, vol. 381, no. 1, p. 367-376. Blackwell Publishing Ltd
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:298129
    Summary
    The reionization of the Universe has profound effects on the way galaxies form and on their observed properties at later times. Of particular importance is the relative timing of the reionization history of a region and its halo assembly history, which can affect the nature of the first stars formed in that region, the properties and radial distribution of its stellar halo, globular cluster population and its satellite galaxies. We distinguish two basic cases for the reionization of a halo - internal reionization, whereby the stars forming in situ reionize their host galaxy, and external reionization, whereby the progenitor of a galaxy is reionized by external radiation before its own stars are able to form in sufficient numbers. We use a set of large-scale radiative transfer and structure formation simulations, based on cosmologies derived from both Wilkinson Microwave Anisotropy Probe (WMAP) one-year and WMAP three-year data, to evaluate the mean reionization redshifts and the probability of internal/external reionization for Local Group-like systems, galaxies in the field and central cD galaxies in clusters. We find that these probabilities are strongly dependent on the underlying cosmology and the efficiency of photon production, but also on the halo mass. There is a rapid transition between predominantly external and predominantly internal reionization at a mass scale of ∼1012 M⊙ (corresponding roughly to L* galaxies), with haloes less massive than this being reionized preferentially from distant sources. We provide a fit for the reionization redshift as a function of halo mass, which could be helpful to parametrize reionization in semi-analytical models of galaxy formation on cosmological scales. We find no statistical correlation between the reionization history of field galaxies and their environment