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We have presented preliminary results from simulations of CDM halos that are the highest resolution possible using todays supercomputers. These simulations have just begun to resolve sub-kiloparsec scales, giving rise to several important predictions on the global structure and substructure of collisionless dark matter halos. The steep central cusps and abundant dark matter substructure of CDM halos are fundamental and testable predictions.

The phase space structure of halos resulting from complex merger histories are just begining to be resolved with current simulations. We find that tidally stripped debris leaves characteristic structure in phase space and the velocity distributions depends sensitively on the location of the observer within triaxial CDM halos (Evans etal 2000, Ullio etal 2000). However, a great deal of work remains to determine the rate and energy distribution of CDM particles through a detector ~ 1m3 (Copi & Krauss 2001).

The prominence of caustics depends crucially on the small scale power spectrum. Detectable caustic rings require very special initial conditions that are incompatible with the CDM paradigm - namely axial symmetry and locally cold velocity fields.

Future simulations and analytic work will be able to answer the key questions: Is there a smooth component of dark matter on the scale of the solar system? Is the earth likely to be passing through a single cold tidal stream or the superposition of many such streams?

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