The cosmic web and the orientation of angular momenta
  We use a 64$h^{-1}$Mpc dark matter (DM) only cosmological simulation to
examine the large scale orientation of haloes and substructures with respect
the cosmic web. A web classification scheme based on the velocity shear tensor
is used to assign to each halo in the simulation a web type: knot, filament,
sheet or void. Using $\sim10^6$ haloes that span ~3 orders of magnitude in mass
the orientation of the halo's spin and the orbital angular momentum of
subhaloes with respect to the eigenvectors of the shear tensor is examined. We
find that the orbital angular momentum of subhaloes tends to align with the
intermediate eigenvector of the velocity shear tensor for all haloes in knots,
filaments and sheets. This result indicates that the kinematics of
substructures located deep within the virialized regions of a halo is
determined by its infall which in turn is determined by the large scale
velocity shear, a surprising result given the virilaized nature of haloes. The
non-random nature of subhalo accretion is thus imprinted on the angular
momentum measured at z = 0. We also find that haloes' spin axis is aligned with
the third eigenvector of the velocity shear tensor in filaments and sheets: the
halo spin axis points along filaments and lies in the plane of cosmic sheets.
