A parsec-resolution simulation of the Antennae galaxies: Formation of
  star clusters during the merger
  We present a hydrodynamical simulation of an Antennae-like galaxy merger at
parsec resolution, including a multi-component model for stellar feedback and
reaching numerical convergence in the global star formation rate for the first
time. We analyse the properties of the dense stellar objects formed during the
different stages of the interaction. Each galactic encounter triggers a
starburst activity, but the varying physical conditions change the triggering
mechanism of each starburst. During the first two pericenter passages, the
starburst is spatially extended and forms many star clusters. However, the
starburst associated to the third, final passage is more centrally
concentrated: stars form almost exclusively in the galactic nucleus and no new
star cluster is formed. The maximum mass of stars clusters in this merger is
more than 30 times higher than those in a simulation of an isolated Milky
Way-like galaxy. Antennae-like mergers are therefore a formation channel of
young massive clusters possibly leading to globular clusters. Monitoring the
evolution of a few clusters reveals the diversity of formation scenarios
including the gathering and merger of gas clumps, the monolithic formation and
the hierarchical formation in sub-structures inside a single cloud. Two stellar
objects formed in the simulation yield the same properties as ultra-compact
dwarf galaxies. They share the same formation scenario than the most massive
clusters, but have a larger radius either since birth, or get it after a
violent interaction with the galactic center. The diversity of environments
across space and time in a galaxy merger can account for the diversity of the
stellar objects formed, both in terms of mass and size.
