Tidally induced bars of galaxies in clusters
  Using N-body simulations we study the formation and evolution of tidally
induced bars in disky galaxies in clusters. Our progenitor is a massive,
late-type galaxy similar to the Milky Way, composed of an exponential disk and
an NFW dark matter halo. We place the galaxy on four different orbits in a
Virgo-like cluster and evolve it for 10 Gyr. As a reference case we also evolve
the same model in isolation. Tidally induced bars form on all orbits soon after
the first pericenter passage and survive until the end of the evolution. They
appear earlier, are stronger, longer and have lower pattern speeds for tighter
orbits. Only for the tightest orbit the properties of the bar are controlled by
the orientation of the tidal torque from the cluster at pericenters. The
mechanism behind the formation of the bars is the angular momentum transfer
from the galaxy stellar component to its halo. All bars undergo extended
periods of buckling instability that occur earlier and lead to more pronounced
boxy/peanut shapes when the tidal forces are stronger. Using all simulation
outputs of galaxies at different evolutionary stages we construct a toy model
of the galaxy population in the cluster and measure the average bar strength
and bar fraction as a function of clustercentric radius. Both are found to be
mildly decreasing functions of radius. We conclude that tidal forces can
trigger bar formation in cluster cores, but not in the outskirts, and thus
cause larger concentrations of barred galaxies towards cluster center.
