Pavel Kroupa: Satellite Galaxies

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Dark matter, cosmology and progress

The Vast Polar Structure (VPOS) of the Milky Way

VPOS: Pawlowski et al. (2012)
Video of the VPOS including all currently (April 2012) known satellite galaxies plus all young halo globular clusters plus all known stellar and gaseous streams (from Pawlowski, Pflamm-Altenburg & Kroupa, 2012, MNRAS, in press). The centrtal blue line in the video is the Milky Way seen edge-on. The grey equatorial regions indicate the zones which are obscured by the disk of the Milky Way.

The VPOS extends from at least about 10 kpc from the Galactic centre to probably beyond 250 kpc. It has a thickness/diameter ratio of about 1:10.

The existence of this vast phase-space correlated structure is essentially a disproof of the satellite galaxies being individual dark-matter dominated primordial satellites that individually fell-in to the Milky Way dark matter halo. The only physically sensible origin of the VPOS is a collision of the Milky Way with another young gas-rich galaxy about 11 Gyr ago such that the presently still visible material formed then from the gas-rich tidal arms drawn out from the other galaxy as it passed the young MW. Such models have been computed and very nicely fit the observed VPOS: Pawlowski et al. (2011, A & A)

The Disk of Satellites of the Milky Way

The Disk of Satellites including all currently (July 2010) known satellites. See Fig.4 in Kroupa et al. (2010, A & A). Here, the upper panel shows the fitted edge-on DoS with dashed lines indicating 1xDelta_min (rather than 1.5xDelta_min in Fig.4).

A movie of the whole vast polar structure (VPOS), of which the here shown satellites are only a part of the population, is available above.


For a visualisation of the three-dimensional distribution of the satellite galaxies about the Milky Way (and Andromeda) click on ViSaGE

Note: if choosing to display a disk, its radius is 200kpc.

ViSaGE is a product developed in 2009 by Manuel Hahn in terms of a Bachelor Thesis at the University of Bonn.

Helmut Jerjen: The Stromlo Milky Way Satellite Survey

The SMS program is a critical endeavor to investigate whether the predictions of standard cold dark matter cosmology are consistent with the observed matter distribution in the Milky Way halo.

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