The formation of the young massive cluster B1 in the Antennae galaxies
  (NGC 4038/NGC 4039) triggered by cloud-cloud collision
  The Antennae Galaxies is one of the starbursts in major mergers. Tsuge et al.
(2020) showed that the five giant molecular complexes in the Antennae Galaxies
have signatures of cloud-cloud collisions based on the ALMA archival data at 60
pc resolution. In the present work we analyzed the new CO data toward the super
star cluster (SSC) B1 at 14 pc resolution obtained with ALMA, and confirmed
that two clouds show complementary distribution with a displacement of $\sim$70
pc as well as the connecting bridge features between them. The complementary
distribution shows a good correspondence with the theoretical collision model
(Takahira et al. 2014), and indicates that SSC B1 having $\sim$10$^{6}$
$M$$_{\odot}$ was formed by the trigger of a cloud-cloud collision with a time
scale of $\sim$1Myr, which is consistent with the cluster age. It is likely
that SSC B1 was formed from molecular gas of $\sim$10$^{7}$ $M$$_{\odot}$ with
a star formation efficiency of $\sim$10 % in 1 Myr. We identified a few places
where additional clusters are forming. Detailed gas motion indicates stellar
feedback in accelerating gas is not effective, while ionization plays a role in
evacuating the gas around the clusters at a $\sim$30-pc radius. The results
have revealed the details of the parent gas where a cluster having mass similar
to a globular is being formed.
