  Satellites are not randomly distributed around their central galaxies but
show polar and planar structures. In this paper, we investigate the
axis-asymmetry or lopsidedness of satellite galaxy distributions around
isolated galaxies in a hydrodynamic cosmological simulation. We find a
statistically significant lopsided signal by studying the angular distribution
of the satellite galaxies' projected positions around isolated central galaxies
in a two-dimensional plane. The signal is dependent on galaxy mass, color and
large-scale environment. Satellites that inhabit low-mass blue hosts, or
located further from the hosts show the most lopsided signal. Galaxy systems
with massive neighbors exhibit stronger lopsidedness. This satellite
axis-asymmetry signal also decreases as the universe evolves. Our findings are
in agreement with recent observational results, and they provide a useful
perspective for studying galaxy evolution, especially on the satellite
accretion, internal evolution and interaction with the cosmic large-scale
structure.
