  Tidal disruption events occur when a star is disrupted by a supermassive
black hole, resulting in an elongated stream of gas that partly falls back to
pericenter. Due to apsidal precession, the returning stream may collide with
itself, leading to a self-crossing shock that launches an outflow. If the black
hole spins, this collision may additionally be affected by Lense-Thirring
precession that can cause an offset between the two stream components. We study
the impact of this effect on the outflow properties by carrying out local
simulations of collisions between offset streams. As the offset increases, we
find that the geometry of the outflow becomes less spherical and more
collimated along the directions of the incoming streams, with less gas getting
unbound by the interaction. However, even the most grazing collisions we
consider significantly affect the trajectories of the colliding gas, likely
promoting subsequent strong interactions near the black hole and rapid disc
formation. We analytically compute the dependence of the offset to stream width
ratio, finding that even slowly spinning black holes can cause both strong and
grazing collisions. We propose that the deviation from outflow sphericity may
enhance the self-crossing shock luminosity due to a reduction of adiabatic
losses, and cause significant variations of the efficiency at which X-ray
radiation from the disc is reprocessed to the optical band depending on the
viewing angle. These potentially observable features hold the promise of
constraining the black hole spin from tidal disruption events.

High Energy Astrophysical Phenomena