Satellite alignment. I. Distribution of substructures and their dependence on assembly history from n-body simulations

Yang Ocean Wang, W. P. Lin, X. Kang, Aaron Dutton, Yu Yu, Andrea Maccio

    Research output: Contribution to journalArticle

    Abstract

    Observations have shown that the spatial distribution of satellite galaxies is not random, but aligned with the major axes of central galaxies. This alignment is dependent on galaxy properties, such that red satellites are more strongly aligned than blue satellites. Theoretical work conducted to interpret this phenomenon has found that it is due to the non-spherical nature of dark matter halos. However, most studies overpredict the alignment signal under the assumption that the central galaxy shape follows the shape of the host halo. It is also not clear whether the color dependence of alignment is due to an assembly bias or an evolution effect. In this paper we study these problems using a cosmological N-body simulation. Subhalos are used to trace the positions of satellite galaxies. It is found that the shapes of dark matter halos are mis-aligned at different radii. If the central galaxy shares the same shape as the inner host halo, then the alignment effect is weaker and agrees with observational data. However, it predicts almost no dependence of alignment on the color of satellite galaxies, though the late accreted subhalos show stronger alignment with the outer layer of the host halo than their early accreted counterparts. We find that this is due to the limitation of pure N-body simulations where satellite galaxies without associated subhalos ("orphan galaxies") are not resolved. These orphan (mostly red) satellites often reside in the inner region of host halos and should follow the shape of the host halo in the inner region.

    Original languageEnglish (US)
    Article number8
    JournalAstrophysical Journal
    Volume786
    Issue number1
    DOIs
    StatePublished - May 1 2014

    Fingerprint

    substructures
    assembly
    alignment
    histories
    galaxies
    halos
    history
    simulation
    orphan
    dark matter
    color
    distribution
    spatial distribution
    radii

    Keywords

    • dark matter
    • Galaxy: halo
    • Galaxy: structure
    • methods: numerical
    • methods: statistical

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Cite this

    Satellite alignment. I. Distribution of substructures and their dependence on assembly history from n-body simulations. / Wang, Yang Ocean; Lin, W. P.; Kang, X.; Dutton, Aaron; Yu, Yu; Maccio, Andrea.

    In: Astrophysical Journal, Vol. 786, No. 1, 8, 01.05.2014.

    Research output: Contribution to journalArticle

    Wang, Yang Ocean ; Lin, W. P. ; Kang, X. ; Dutton, Aaron ; Yu, Yu ; Maccio, Andrea. / Satellite alignment. I. Distribution of substructures and their dependence on assembly history from n-body simulations. In: Astrophysical Journal. 2014 ; Vol. 786, No. 1.
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