  We present our discovery of observational evidence for the coherence between
galaxy rotation and the average line-of-sight motion of neighbors. We use the
Calar Alto Legacy Integral Field Area (CALIFA) survey data analyzed with the
Python CALIFA STARLIGHT Synthesis Organizer (PyCASSO) platform, and the
NASA-Sloan Atlas (NSA) catalog. After estimating the projected angular momentum
vectors of 445 CALIFA galaxies, we build composite maps of their neighbor
galaxies on the parameter space of line-of-sight velocity versus projected
distance. The composite radial profiles of the luminosity-weighted mean
velocity of neighbors show striking evidence for dynamical coherence between
the rotational direction of the CALIFA galaxies and the average moving
direction of their neighbor galaxies. The signal of such dynamical coherence is
significant for the neighbors within 800 kpc distance from the CALIFA galaxies,
for which the luminosity-weighted mean velocity is as large as 61.7+/-17.6 km/s
(3.5-sigma significance to bootstrap uncertainty) when the angular momentum is
measured at R_e<R<=2R_e of each CALIFA galaxy. In the comparison of the
subsamples, we find that faint, blue or kinematically misaligned galaxies show
stronger coherence with neighbor motions than bright, red or kinematically
well-aligned galaxies do. Our results indicate that (1) the rotation of a
galaxy (particularly at its outskirt) is significantly influenced by
interactions with its neighbors up to 800 kpc, (2) the coherence is
particularly strong between faint galaxies and bright neighbors, and (3) galaxy
interactions often cause internal kinematic misalignment or possibly even
kinematically distinct cores.
