Clumps and streams in the local dark matter distribution
May, 2008Citations per year
Abstract: (arXiv)
In the standard 'cold dark matter' cosmological model structures form and grow by merging of smaller subunits. Cosmological simulations have demonstrated that most mergers are incomplete: many halos survive and orbit as ``subhalos'' within their hosts. So far, subhalos have not been resolved in the very inner halo and it was unclear whether the local dark matter would be smooth or clumpy. We have simulated the formation of the Galactic halo at an unprecedented resolution that allows us for the first time to resolve local substructure. We find hundreds of very concentrated dark matter clumps surviving near the solar system, as well as numerous cold streams. These small, dark Galactic ghost halos are survivers of the merging hierarchy and have properties remarkably close to their isolated counterparts in the field: both have cuspy inner density profiles and both contain the same relative amount of substructure. These predictions have various implications: Dark matter annihilation rates would be significantly enhanced. They match the inner densities and phase-space densities of the recently discovered faint, dark matter-dominated dwarf satellites and they compare well with substructure constraints from gravitational lensing.Note:
- 13 pages, 4 figures, submitted to Nature. Full version of Figure 1 available at http://www.ucolick.org/~diemand/vl2/fig1.png
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