Effects of galaxy--satellite interactions on bar formation
  Aims. We aim to show how encounters with low-mass satellite galaxies may
alter the bar formation in a Milky Way-like disc galaxy. Methods. We use
high-resolution N-body simulations of a disc galaxy prone to mild bar
instability. For realistic initial conditions of satellites, we take advantage
of cosmological simulations of Milky Way-like dark matter haloes. Results. The
satellites may have a significant impact on the time of bar formation. Some
runs with satellites demonstrate a delay, while others show an advancement in
bar formation compared to the isolated run, with such time differences reaching
$\sim$ 1 Gyr. Meanwhile, the final bar configuration, including its very
appearance and the bar characteristics such as the pattern speed and the
exponential growth rate of its amplitude are independent of the number of
encounters and their orbits. The contribution of satellites with masses below
$10^9 M_{\odot}$ is insignificant, unless their pericentre distances are small.
We suggest that the encounters act indirectly via inducing perturbations across
the disc that evolve to delayed waves in the central part and interfere with an
emerging seed bar. The predicted effect for the present-day host galaxy is
expected to be even more significant at redshifts $z \gtrsim 0.5$.
