A novel determination of the local dark matter density
  We present a novel study on the problem of constructing mass models for the
Milky Way, concentrating on features regarding the dark matter halo component.
We have considered a variegated sample of dynamical observables for the Galaxy,
including several results which have appeared recently, and studied a 7- or
8-dimensional parameter space - defining the Galaxy model - by implementing a
Bayesian approach to the parameter estimation based on a Markov Chain Monte
Carlo method. The main result of this analysis is a novel determination of the
local dark matter halo density which, assuming spherical symmetry and either an
Einasto or an NFW density profile is found to be around 0.39 GeV cm$^{-3}$ with
a 1-$\sigma$ error bar of about 7%; more precisely we find a $\rho_{DM}(R_0) =
0.385 \pm 0.027 \rm GeV cm^{-3}$ for the Einasto profile and $\rho_{DM}(R_0) =
0.389 \pm 0.025 \rm GeV cm^{-3}$ for the NFW. This is in contrast to the
standard assumption that $\rho_{DM}(R_0)$ is about 0.3 GeV cm$^{-3}$ with an
uncertainty of a factor of 2 to 3. A very precise determination of the local
halo density is very important for interpreting direct dark matter detection
experiments. Indeed the results we produced, together with the recent accurate
determination of the local circular velocity, should be very useful to
considerably narrow astrophysical uncertainties on direct dark matter
detection.
