Within the ΛCDM cosmogony small dark matter halos are predicted to be very abundant. A large majority of these small haloes however, will never get massive enough to form stars and lighten up and will therefore remain "dark", but may leave dynamical imprints in luminous galaxies.

This motivates our poster on a suite of controlled simulations of dwarf galaxies and dark satellites. We simulate mergers between a dark satellite and a disky dwarf galaxy both with and without gas. The collisionless mergers show that dark satellites do perturb the disky dwarf, leading to significant thickening and important morphological changes. This thickening depends strongly on the mass ratios of the satellite to the host disk, which leads us to conclude that such encounters are likely to be important in the evolution of dwarf galaxies.

Our simulations with gas show that the accretion of a dark satellite can induce a starburst. The increase in the star formation rate ranges from a few to factors greater than ten, depending on the orbital characteristics of the encounter. Interestingly, in such cases the dominant starburst is located in the center of the (eventually) accreted dark satellite, thereby lightening it for a brief period of time after which it finally merges with the dwarf.