Physical properties of superbubbles in the Antennae galaxies
  Mass outflow generated by the dynamical feedback from massive stars is
currently a topic of high interest. Using a purpose-developed analysis
technique, and taking full advantage of the high kinematic and angular
resolution of our instrument we have detected a number of expanding
superbubbles in the interacting pair of galaxies Arp 244 (NGC 4038/9) commonly
known as the Antennae. We use a Fabry-P\'erot interferometer GH{\alpha}FaS to
measure the profile of H{\alpha} in emission over the full extent of the
object, except for the extended HI tails. The superbubbles are found centred on
most of the brightest HII regions, especially in the overlap area of the two
merging galaxies. We use measured sizes, expansion velocities and luminosities
of the shells to estimate most of the physical parameters of the bubbles,
including the kinetic energy of the expansion. In order to assess the validity
of our results and approximations we perform a hydrodynamic simulation and
manage to reproduce well our best measured superbubble with reasonable physical
input assumptions. We also study the sources of ionization of the shells,
finding that at the current, quite late stage of expansion, radiation from the
remaining stars dominates, though the effect of supernova shocks can still be
noted.
