Filamentary accretion cannot explain the orbital poles of the Milky Way satellites

M. S. Pawlowski, P. Kroupa, G. Angus, K. S. de Boer, B. Famaey, G. Hensler

    Research output: Contribution to journalArticle

    51 Citations (Scopus)

    Abstract

    Several scenarios have been suggested to explain the phase-space distribution of the Milky Way (MW) satellite galaxies in a disc of satellites (DoS). To quantitatively compare these different possibilities, a new method analysing angular momentum directions in modelled data is presented. It determines how likely it is to find sets of angular momenta as concentrated and as close to a polar orientation as is observed for the MW satellite orbital poles. The method can be easily applied to orbital pole data from different models. The observed distribution of satellite orbital poles is compared to published angular momentum directions of subhaloes derived from six cosmological state-of-the-art simulations in the Aquarius project. This tests the possibility that filamentary accretion might be able to naturally explain the satellite orbits within the DoS. For the most likely alignment of main halo and MW disc spin, the probability to reproduce the MW satellite orbital pole properties turns out to be less than 0.5per cent in the Aquarius models. Even an isotropic distribution of angular momenta has a higher likelihood to produce the observed distribution. The two Via Lactea cosmological simulations give results similar to the Aquarius simulations. Comparing instead with numerical models of galaxy interactions gives a probability of up to 90per cent for some models to draw the observed distribution of orbital poles from the angular momenta of tidal debris. This indicates that the formation as tidal dwarf galaxies in a single encounter is a viable, if not the only, process to explain the phase-space distribution of the MW satellite galaxies.

    Original languageEnglish
    Pages (from-to)80-92
    Number of pages13
    JournalMonthly Notices of the Royal Astronomical Society
    Volume424
    Issue number1
    DOIs
    Publication statusPublished - Jul 2012

    Fingerprint

    poles
    accretion
    orbitals
    angular momentum
    galaxies
    interacting galaxies
    satellite orbits
    simulation
    dwarf galaxies
    debris
    encounters
    halos
    distribution
    alignment

    All Science Journal Classification (ASJC) codes

    • Space and Planetary Science
    • Astronomy and Astrophysics

    Cite this

    Pawlowski, M. S. ; Kroupa, P. ; Angus, G. ; de Boer, K. S. ; Famaey, B. ; Hensler, G. / Filamentary accretion cannot explain the orbital poles of the Milky Way satellites. In: Monthly Notices of the Royal Astronomical Society. 2012 ; Vol. 424, No. 1. pp. 80-92.
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    Filamentary accretion cannot explain the orbital poles of the Milky Way satellites. / Pawlowski, M. S.; Kroupa, P.; Angus, G.; de Boer, K. S.; Famaey, B.; Hensler, G.

    In: Monthly Notices of the Royal Astronomical Society, Vol. 424, No. 1, 07.2012, p. 80-92.

    Research output: Contribution to journalArticle

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