Author(s): Cinthya N. Herrera4, Francois Boulanger3, Edith G. Falgarone1, Guillaume Pineau des Forets3, Santiago Garcia-Burillo5, Daisuke Iono4, Pierre Guillard2
Institution(s): 1. ENS, 2. IAP, 3. Institut d' Astrophysique Spatiale, 4. NAOJ, 5. OAN
The Antennae galaxies are a spectacular example of a burst of star formation triggered by the encounter of two galaxies, being an ideal source to understand how the dynamics of galaxy mergers trigger the star formation. Most of the newly formed stars are observed in massive clusters, potentially the progenitors of globular clusters. In the Antennae, their formation must involve a complex interplay of merger-driven gas dynamics, turbulence fed by galaxy interaction and dissipation of the gas kinetic energy.
We will present archive ALMA CO(3-2) and new 13CO(2-1) and C18O(2-1) Cycle 2 observations, at 50 pc resolution, and VLT near-IR H2 spectro-imaging observations. We will show an analysis of the excitation of the CO gas in the region where the two galaxies collide, and demonstrate that most of the H2 emission associated with this gas is shock-excited. We will focus on a compact, bright H2 source, associated with cold molecular gas and dust continuum emission, located where the velocity gradient in the interaction region is observed to be the largest. The characteristics of this source suggest that we are witnessing the formation, initiated by turbulent dissipation, of a cloud massive enough to form a super star cluster within 1 Myr.