  The intrinsic alignment of galaxy shapes (by means of their angular momentum)
and their cross-correlation with the surrounding dark matter tidal field are
investigated using the 160 000, z=1.2 synthetic galaxies extracted from the
high-resolution cosmological hydrodynamical simulation Horizon-AGN. One- and
two-point statistics of the spin of the stellar component are measured as a
function of mass and colour. For the low-mass galaxies, this spin is locally
aligned with the tidal field `filamentary' direction while, for the high-mass
galaxies, it is perpendicular to both filaments and walls. The bluest galaxies
of our synthetic catalog are more strongly correlated with the surrounding
tidal field than the reddest galaxies, and this correlation extends up to 10
Mpc/h comoving distance. We also report a correlation of the projected
ellipticities of blue, intermediate mass galaxies on a similar scale at a level
of 10^(-4) which could be a concern for cosmic shear measurements. We do not
report any measurable intrinsic alignments of the reddest galaxies of our
sample. This work is a first step toward the use of very realistic catalog of
synthetic galaxies to evaluate the contamination of weak lensing measurement by
the intrinsic galactic alignments.
