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Astrophysics, Cosmology and Extragalactic Astrophysics, astro-ph.CO,High Energy Physics - Phenomenology, hep-ph
Abstract:
Dark matter N-body simulations suggest that the velocity distribution of dark
matter is anisotropic. In this work we employ a mass model for the Milky Way
whose parameters are determined from a fit to kinematical data. Then we adopt
an ansatz for the dark matter phase space distribution which allows to
construct self-consistent halo models which feature a degree of anisotropy as a
function of the radius such as suggested by the simulations. The resulting
velocity distributions are then used for an analysis of current data from dark
matter direct detection experiments. We find that velocity distributions which
are radially biased at large galactocentric distances (up to the virial radius)
lead to an increased high velocity tail of the local dark matter distribution.
This affects the interpretation of data from direct detection experiments,
especially for dark matter masses around 10 GeV, since in this region the high
velocity tail is sampled. We find that the allowed regions in the dark matter
mass-cross section plane as indicated by possible hints for a dark matter
signal reported by several experiments as well as conflicting exclusion limits
from other experiments shift in a similar way when the halo model is varied.
Hence, it is not possible to improve the consistency of the data by referring
to anisotropic halo models of the type considered in this work.
