Search for Galactic warp signal in Gaia DR1 proper motions
  The nature and origin of the Galactic warp represent one of the open
questions posed by Galactic evolution. Thanks to Gaia high precision absolute
astrometry, steps towards the understanding of the warp's dynamical nature can
be made. Indeed, proper motions for long-lived stable warp are expected to show
measurable trends in the component vertical to the galactic plane. Within this
context, we search for the kinematic warp signal in the first Gaia data release
(DR1). By analyzing distant spectroscopically-identified OB stars in the
Hipparcos subset in Gaia DR1, we find that the kinematic trends cannot be
explained by a simple model of a long-lived warp. We therefore discuss possible
scenarios for the interpretation of the obtained results. We also present
current work in progress to select a larger sample of OB star candidates from
the Tycho-Gaia Astrometric Solution (TGAS) subsample in DR1, and delineate the
points that we will be addressing in the near future.
