Bars in dark matter-dominated dwarf galaxy discs
  We study the shape and kinematics of simulated dwarf galaxy discs in the
APOSTLE suite of $\Lambda$CDM cosmological hydrodynamical simulations. We find
that a large fraction of these gas-rich, star-forming discs show weak bars in
their stellar component, despite being dark matter-dominated systems. The bar
pattern shape and orientation reflect the ellipticity of the dark matter
potential, and its rotation is locked to the slow figure rotation of the
triaxial dark halo. The bar-like nature of the potential induces non-circular
motions in the gas component, including strong bisymmetric flows that can be
readily seen as m=3 harmonic perturbations in the HI line-of-sight velocity
fields. Similar bisymmetric flows are seen in many galaxies of the THINGS and
LITTLE THINGS surveys, although on average their amplitudes are a factor of ~2
weaker than in our simulated discs. Our results indicate that bar-like patterns
may arise even when baryons are not dominant, and that they are common enough
to warrant careful consideration when analyzing the gas kinematics of dwarf
galaxy discs.
