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Substructure in CDM Halos and the Heating of Stellar Disks
Numerical simulations have revealed the presence of long-lived substructure
in Cold Dark Matter (CDM) halos. These surviving cores of past merger and
accretion events vastly outnumber the known satellites of the Milky Way. This
finding has prompted suggestions that substructure in cold dark matter (CDM)
halos may be incompatible with observation and in conflict with the presence of
thin, dynamically fragile stellar disks. N-body simulations of a
disk/bulge/halo model of the Milky Way that includes several hundred dark
matter satellites with masses, densities and orbits derived from
high-resolution cosmological CDM simulations indicate that substructure plays
only a minor dynamical role in the heating of the disk. This is because the
orbits of satellites seldom take them near the disk, where their tidal effects
are greatest. We conclude that substructure might not preclude virialized CDM
halos from being acceptable hosts of thin stellar disks like that of the Milky
Way.Comment: Presented at the Yale Symposium "The Shape of Galaxies and their
Halos", ed. P.Nataraja
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