Insights on the Milky Way bulge formation from the correlations between
  kinematics and metallicity
  Two main scenarios for the formation of the Galactic bulge are invoked, the
first one through gravitational collapse or hierarchical merging of subclumps,
the second through secular evolution of the Galactic disc. We aim to constrain
the formation of the Galactic bulge through studies of the correlation between
kinematics and metallicities in Baade's Window (l=1, b=-4) and two other fields
along the bulge minor axis (l=0, b=-6 and b=-12). We combine the radial
velocity and the [Fe/H] measurements obtained with FLAMES/GIRAFFE at the VLT
with a spectral resolution of R=20000, plus for the Baade's Window field the
OGLE-II proper motions, and compare these with published N-body simulations of
the Galactic bulge. We confirm the presence of two distinct populations in
Baade's Window found in Hill et al. 2010: the metal-rich population presents
bar-like kinematics while the metal-poor population shows kinematics
corresponding to an old spheroid or a thick disc one. In this context the
metallicity gradient along the bulge minor axis observed by Zoccali et al.
(2008), visible also in the kinematics, can be related to a varying mix of
these two populations as one moves away from the Galactic plane, alleviating
the apparent contradiction between the kinematic evidence of a bar and the
existence of a metallicity gradient. We show evidences that the two main
scenarios for the bulge formation co-exist within the Milky Way bulge.
