Anisotropies in the Distribution of Satellite Galaxies

We find that satellites of isolated disk galaxies at projected radii between300 and 500 kpc are distributed asymmetrically about the parent galaxy andaligned preferentially with the disk minor axis. The dynamical timescale atthese radii is sufficiently long that the shape of this distribution mustreflect the formation history of the outer halo rather than its internalevolution. We also find that the orbital angular momenta of satellites atprojected major axis distances of $\ltsim$ 200 kpc tend to align with that ofthe central disk. These results demonstrate that satellites are dynamicallyrelated to their primary galaxy. Satellites drawn from current simulations ofhierarchical galaxy formation exhibit neither the systematic alignment nor thenet rotation with the central disk that we find in the data.Comment: 15 pages, submitted to ApJ