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arXiv · astro-ph/0610933

The spatial distribution of the Milky Way and Andromeda satellite galaxies

M. Metz·P. Kroupa·H. Jerjen
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Abstract

There are two fundamentally different physical origins of faint satellite galaxies: cosmological sub-structures that contain shining baryons and the fragmentation of gas-rich tidal arms thrown out from interacting galaxies during hierarchical structure formation. The latter tidal-dwarf galaxies (TDG) may form populations with correlated orbital angular momenta about their host galaxies. The existence of TDGs is a stringent necessity because they arise as a result of fundamental physical principals. We determine the significance of the apparent disc-like distribution of Milky Way (MW) satellite galaxies. The distribution of the MW satellites is found to be inconsistent with an isotropic or prolate DM sub-structure distribution at a 99.5 per cent level including the recently discovered UMa and CVn dwarf spheroidal galaxies. The distribution is extremely oblate and inclined by about $88\degr$ with respect to the the MW disc. We also apply the methods to Andromeda's (M31) satellite galaxies using two recently published data-sets. It can not be excluded that the whole population of M31 companions is drawn randomly from an isotropic parent distribution. However, two subsamples of Andromeda satellites are identified which have disc-like features. [abbreviated]

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M. Metz, P. Kroupa, H. Jerjen. 2006-10-31. The spatial distribution of the Milky Way and Andromeda satellite galaxies. https://doi.org/10.1111/j.1365-2966.2006.11228.x

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