  A recent study conducted using CALIFA survey data (Lee et al, 2019b) has
found that the orbital motions of neighbor galaxies are coherent with the spin
direction of a target galaxy on scales of many Megaparsecs. We study this so
called `large-scale coherence' phenomena using N-body cosmological simulations.
We confirm a strong coherence signal within 1 Mpc/h of a target galaxy,
reaching out to 6 Mpc/h. We divide the simulation halos into subsamples based
on mass, spin, merger history and local halo number density for both target and
neighbor halos. We find a clear dependency on the mass of the target halo only.
Another key parameter was the local number density of both target and neighbor
halos, with high density regions such as clusters and groups providing the
strongest coherence signals, rather than filaments or lower density regions.
However we do not find a clear dependency on halo spin or time since last major
merger. The most striking result we find is that the signal can be detected up
to~15Mpc/h from massive halos. These result provide valuable lessons for how
observational studies could more clearly detect coherence, and we discuss the
implications of our results for the origins of large-scale coherence.
