A-type stars in the Canada-France Imaging Survey II. Tracing the height
  of the disc at large distances with Blue Stragglers
  We present the kinematics of Blue Straggler (BS) stars identified in the
Canada-France-Imaging-Survey (CFIS), covering 4000 deg$^2$ on the sky in the
$u$-band. The BS sample, characterised through CFIS and Pan-STARRS photometry,
has been kinematically decomposed into putative halo and disc populations after
cross-matching with Gaia astrometry and SDSS/SEGUE/LAMOST spectroscopy. This
decomposition clearly reveals the strong flaring of the outer Milky Way disc.
In particular, we show that we can detect this flaring up to a vertical height
of $|Z| \simeq 8$ kpc at a Galactocentric distance of $R\sim $27 kpc. While
some small level of flaring is expected for extended discs built up by radial
migration, we demonstrate that this observed very strong flaring of the Milky
Way disc is more likely consistent with it being dynamically heated by the
repeated passage of the Sagittarius dwarf spheroidal galaxy through the
midplane.
