Document Mass Profiles and Shapes of Cosmological Structures
G.A. Mamon, F. Combes, C. Deffayet and B. Fort (eds)
EAS Publications Series, 20 (2006) 135-138
DOI: 10.1051/eas:2006060
Lost and found dark matter in elliptical galaxies
F. Stoehr1, G.A. Mamon1, A. Dekel2 and T.J. Cox31 IAP, 98 bis Bd. Arago, 75014 Paris, France
2 Hebrew University, Jerusalem, Israel
3 Harvard-Smithsonian CfA, 60 Garden St, Cambridge, MA 02138, USA
Abstract
The kinematical properties of elliptical galaxies formed during the mergers
of equal mass, stars+gas+dark matter spiral galaxies are compared to the
observed low velocity
dispersions found for planetary nebulae on the outskirts of ellipticals,
which have been interpreted as pointing to a lack of dark matter in
ellipticals
(which poses a problem for the standard model of galaxy formation).
We find that the velocity dispersion profiles of the stars in the
simulated ellipticals
match well the observed ones.
The low outer stellar velocity dispersions are mainly caused by the radial
orbits of the outermost stars, which, for a given binding energy must have
low angular momentum to reach their large radial distances, usually driven
out along tidal tails.
© EAS, EDP Sciences 2006