The formation of the young massive cluster B1 in the Antennae galaxies (NGC 4038/NGC 4039) triggered by cloud-cloud collision
Abstract
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 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 106 M was formed by the trigger of a cloud-cloud collision with a time scale of 1Myr, which is consistent with the cluster age. It is likely that SSC B1 was formed from molecular gas of 107 M with a star formation efficiency of 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 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.