Reinforcing the link between the double red clump and the X-shaped bulge
  of the Milky Way
  The finding of a double red clump in the luminosity function of the Milky Way
bulge has been interpreted as evidence for an X-shaped structure. Recently, an
alternative explanation has been suggested, where the double red clump is an
effect of multiple stellar populations in a classical spheroid. In this letter
we provide an observational assessment of this scenario and show that it is not
consistent with the behaviour of the red clump across different lines of sight,
particularly at high distances from the Galactic plane. Instead, we confirm
that the shape of the red clump magnitude distribution closely follows the
distance distribution expected for an X-shaped bulge at critical Galactic
latitudes. We also emphasize some key observational properties of the bulge red
clump that should not be neglected in the search for alternative scenarios.
