Issue EAS Publications Series Volume 10, 2003 JENAM 2002, Galactic & Stellar Dynamics Page(s) 133 DOI 10.1051/eas2003159

Galactic & Stellar Dynamics
C. Boily, P. Patsis, S. Portegies Zwart, R. Spurzem and C. Theis (eds)
EAS Publications Series, Vol. 10, 2003
DOI: 10.1051/eas:2003159

The mechanics of dark matter halo formation

C.M. Boily¹, T. Tsuchiya^{2, 3} and R. Spurzem<sup>2

1</sup>  Observatoire Astronomique, 11 rue de l'Université, 67000 Strasbourg, France
²  Astronomisches Rechen-Institut, Mönchhofstrasse 12-14, 69120 Heidelberg, Germany
³  Max-Planck-Institut für Astronomie, Königstuhl, 69117 Heidelberg, Germany ^* Current address: SGI Japan Ltd., 668-3, Moto-zaimoku-cho, Fushimi-ku, Kyoto 612-8043, Japan

Abstract
We study the survival of sub-structures (clumps) within larger self-gravitating galaxies or dark matter halos. Building on scaling relations obtained from N-body calculations of violent relaxation, we argue that the tidal field of galaxies and halos can only destroy sub-structures if spherical symmetry is imposed at formation. Unless the larger halo is built up from a few large clumps, we find that clump-clump encounters are unlikely to homogenise the halo on a dynamical timescale. Phase-mixing would proceed faster in the inner parts and allow for the secular evolution of a stellar disc.

© EAS, EDP Sciences 2003

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