We identify 20 (17 for the first time) kinematically cold streams in
the inner halo of the Milky Way. Our result is based on the observed
spatial and radial velocity distribution of metal-poor main sequence
turn-off (MPMSTO) stars in 117 Sloan Extension for Galactic
Understanding (SEGUE) lines-of-sight. We show that the observed
distribution is consistent with a smooth stellar component of the
Milky Way's halo at large scales, but disagrees significantly at the
radial velocities that correspond to our detections. We prove that
all of our detections are significant to more than 10-sigma and that
we expect only one of our detections to be a false-positive. These
cold streams represent the observable stellar populations of those
dark matter halos that merged to form the Milky Way, and we use our
detections and estimates of our completeness to predict that
approximately 3000 streams are present in the entire inner halo. We
also present preliminary results on our search for radial velocity
substrucutre in the more distant blue horizontal-branch population.
We compare our detections with the very high resolution dark
matter-only Via Lactea simulation to constrain the mapping of dark
matter halos to their stellar content. Finally, we consider the
implications of our detections in the context of the formation of
Milky Way.
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