Tidal Torquing of Elliptical Galaxies in Cluster Environments
  Observational studies of galaxy isophotal shapes have shown that galaxy
orientations are anisotropic: a galaxy's long axis tends to be oriented toward
the center of its host. This radial alignment is seen across a wide range of
scales, from galaxies in massive clusters to small Milky Way type satellite
systems. Recently, this effect has also been detected in dark matter
simulations of cosmological structure, but the degree of alignment of dark
matter substructures in these studies is significantly stronger than seen in
observations. In this paper we attempt to reconcile these two results by
performing high-resolution numerical experiments on N-body multi-component
models of triaxial galaxies orbiting in an external analytical potential. The
large number of particles employed allows us to probe deep into the inner
structure of the galaxy: we show that the discrepancy between observed galaxies
and simulated dark matter halos is a natural consequence of induced radial
shape twisting in the galaxy by the external potential. The degree of twisting
depends strongly on the orbital phase and eccentricity of the satellite, and it
can, under certain conditions, be significant at radii smaller than the dark
matter scale radius. Such internal misalignments will have important
consequences, both for the dynamical evolution of the galaxy itself, and for
mass modeling of galaxies in clustered environments.
