Phase-space structure in the local dark matter distribution and its signature in direct detection experiments

Understand

We study predictions for dark matter phase-space structure near the Sun based on high-resolution simulations of six galaxy halos taken from the Aquarius Project.

• The local DM density distribution is predicted to be remarkably smooth; the density at the Sun differs from the mean over a best-fit ellipsoidal equidensity contour by less than 15% at the 99.9% confidence level.
• The local velocity distribution is also very smooth, but it differs systematically from a (multivariate) Gaussian distribution.
• This is not due to the presence of individual clumps or streams, but to broad features in the velocity modulus and energy distributions that are stable both in space and time and reflect the detailed assembly history of each halo.