Using dwarf satellite proper motions to determine their origin

G. W. Angus, Antonaldo Diaferio, Pavel Kroupa

    Research output: Contribution to journalArticle

    23 Citations (Scopus)

    Abstract

    The highly organized distribution of satellite galaxies surrounding the Milky Way is a serious challenge to the concordance cosmological model. Perhaps the only remaining solution, in this framework, is that the dwarf satellite galaxies fall into the Milky Way's potential along one or two filaments, which may or may not plausibly reproduce the observed distribution. Here we test this scenario by making use of the proper motions of the Fornax, Sculptor, Ursa Minor and Carina dwarf spheroidals, and trace their orbits back through several variations of the Milky Way's potential and account for dynamical friction. The key parameters are the proper motions and total masses of the dwarf galaxies. Using a simple model, we find no tenable set of parameters that can allow Fornax to be consistent with filamentary infall, mainly because the 1σ error on its proper motion is relatively small. The other three must walk a tightrope between requiring a small pericentre (less than 20kpc) to lose enough orbital energy to dynamical friction and avoiding being tidally disrupted. We then employed a more realistic model with host halo mass accretion and found that the four dwarf galaxies must have fallen in at least 5Gyr ago. This time-interval is longer than organized distribution is expected to last before being erased by the randomization of the satellite orbits.

    Original languageEnglish
    Pages (from-to)1401-1409
    Number of pages9
    JournalMonthly Notices of the Royal Astronomical Society
    Volume416
    Issue number2
    DOIs
    Publication statusPublished - Sep 2011

    Fingerprint

    proper motion
    dwarf galaxies
    friction
    galaxies
    satellite orbits
    halos
    filaments
    accretion
    intervals
    orbits
    orbitals
    energy
    distribution
    parameter

    All Science Journal Classification (ASJC) codes

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Cite this

    Angus, G. W. ; Diaferio, Antonaldo ; Kroupa, Pavel. / Using dwarf satellite proper motions to determine their origin. In: Monthly Notices of the Royal Astronomical Society. 2011 ; Vol. 416, No. 2. pp. 1401-1409.
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    Using dwarf satellite proper motions to determine their origin. / Angus, G. W.; Diaferio, Antonaldo; Kroupa, Pavel.

    In: Monthly Notices of the Royal Astronomical Society, Vol. 416, No. 2, 09.2011, p. 1401-1409.

    Research output: Contribution to journalArticle

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