Bar Formation from Galaxy Flybys
  Recently, both simulations and observations have revealed that flybys - fast,
one-time interactions between two galaxy halos - are surprisingly common,
nearing/comparable to galaxy mergers. Since these are rapid, transient events
with the closest approach well outside the galaxy disk, it is unclear if flybys
can transform the galaxy in a lasting way. We conduct collisionless N-body
simulations of three co-planer flyby interactions between pure-disk galaxies to
take a first look at the effects flybys have on disk structure, with particular
focus on stellar bar formation. We find that some flybys are capable of
inciting a bar with bars forming in both galaxies during our 1:1 interaction
and in the secondary during our 10:1 interaction. The bars formed have
ellipticities >0.5, sizes on the order of the host disk's scale length, and
persist to the end of our simulations, ~5 Gyr after pericenter. The ability of
flybys to incite bar formation implies that many processes associated with
secular bar evolution may be more closely tied with interactions than
previously though.
