2025-05-29 –, Main Conference Room
The Galactic Bar is the link between the Milky Way disk and the Galaxy's nuclear environment that is characterized by the Central Molecular Zone (CMZ). Gas in the CMZ is much more dense and abundant as compared to the disk, and it is undergoing extreme physical forces such as shear due to bar motions, a high flux of ionizing radiation and cosmic rays, as well as strong magnetic fields and outflows. John Bally was one of the pioneers to bring all the different phenomena together and to build up a model that describes the CMZ as a whole. Such models are crucial in for the understanding of the formation and processes of the gas flow and the inner workings of the CMZ. I will present a study of a number of clouds that are not part of the regular, bulk bar flow, but are at a much higher velocity dispersion along the same line of sight. We obtained ALMA data in a number of molecular tracers to characterize those clouds. We find strong collisions between gas clouds at about 5deg in Galactic longitude. In addition, we find that some of the clouds have elevated internal Mach numbers. These turbulent clouds show the increase in temperature and they exhibit suppressed star formation. The turbulent clouds almost certainly are in the bar, and they have properties that are typical for the CMZ (including a lower Xco-H2 conversion ratio). This indicates that at least some gas is energized before it reaches the inner Galactic Center. The best physical model is that these clouds are related to material that is overshooting accretion on the inner 100pc cloud only to collide with gas on the opposite Bar side. The loss of angular momentum will eventually drive them back to the CMZ.
