Kinematics and dynamics of Gaia red clump stars
  We analyse the kinematics and dynamics of a homogeneous sample of red clump
stars selected from the second Gaia data release catalogue in the direction of
the Galactic poles. The level of completeness of the sample at heights between
0.6 and 3.5 kpc is asserted by comparison with the 2 Micron All Sky Survey
catalogue. We show that both the density distribution and velocity dispersion
are significantly more perturbed in the North than in the South, in all
analysed regions of our Galactic neighbourhoods. We provide a detailed
assessment of these North-South asymmetries at large heights. We then proceed
to evaluate how such asymmetries could affect determinations of the dynamical
matter density under equilibrium assumptions. We find that a Jeans analysis
delivers relatively similar vertical forces and integrated dynamical surface
densities at large heights above the plane in both hemispheres. At these
heights, the densities of stars and gas are very low and the surface density is
largely dominated by dark matter, which allows to estimate, separately in the
North and South, the local dark matter density derived under equilibrium
assumptions. In the presence of vertical perturbations, such values should be
considered as an upper limit. This Jeans analysis yields values of the local
dark matter density above 2~kpc, $\rho_{\rm DM} \sim 0.013 \, {\rm
M}_\odot/{\rm pc}^3$ ($ \sim 0.509 \, {\rm GeV/cm}^3$) in the perturbed
Northern hemisphere, and $\rho_{\rm DM} \sim 0.010 \, {\rm M}_\odot/{\rm pc}^3$
($ \sim 0.374 \, {\rm GeV/cm}^3$) in the much less perturbed South. As a
comparison, we determine the local dark matter density by fitting a global
phase-space distribution to the data. We end up with a value in the range of
$\rho_{\rm DM} \sim 0.011 - 0.014 \, {\rm M}_\odot/{\rm pc}^3$ in global
agreement with Jeans analysis.
