Dani R. Lipman

From Lipman et al., 2026a showing a top-down view of the best-fitting CMZ orbital model and cataloged molecular cloud positions based on Bayesian synthesis of multi-wavelength data.

Knowing how gas moves around the Galactic Center is a key piece of information for understanding how the Galaxy evolves. When, where, and how many star form is largely connected to where the gas that fuels star formation travels and builds up.

In the 3D CMZ paper series , we present the first ever 3D picture of the CMZ, using multiwavelength data to determine positions of molecular clouds with respect to our suppermassive black hole, SgrA. Lipman et al., 2025 presents new dust extinction techniques to distinguish near vs. far positions of CMZ clouds. In Lipman et al., 2026a, I created a flexible Bayesian framwork to synthesize information from multi-wavelength datasets, and determined the best fitting orbit in position-position-velocity space. This framework is meant to be continually updated with new data, which promises great improvements for the orbital model with upcoming datasets from JWST and Roman.

From Lipman et al., 2026b showing postion-position-velocity distributions of high-velocity compact clouds in the CMZ, detected in ALMA molecular shock tracers. See the interactive web-app of this figure HERE

The extreme kinematics of the Milky Way's CMZ are influenced by processes such as dynamical shearing, cloud collisions, and stellar feedback. The mass flows in this region are innately tied to its unexplained low star formation rate, projected gas asymmetries, and the transportation of material further inwards towards the supermassive black hole at the center. New observations from the ALMA CMZ Exploration Survey (ACES) provide unprecedented details covering the entire inner 2 degrees of the Galaxy at sub-parsec resolutions in dozens of molecular tracers. I led a study utilizing these data to catalog large disturbances in the average CMZ gas flows referred to as high velocity dispersion compact clouds (HVCCs). We use both visual and algorithmic methods to identify 235 HVCC candidates in shocked ACES CS (2-1) gas, and characterize their kinematic morphologies.

Example density projection from Lipman et al. (in prep)

Combining theory and observation provides us with powerful tools to demystify the complex physics of our Galaxy's center. Observational programs using ground-based instruments (e.g. SMA and ALMA) as well as space-based surveys (e.g. Spitzer, Herschel, JWST, and Roman) have made significant progress towards determining the small-scale distributions of gas in the CMZ. But what mechanisms drive or control star formation? How do the physical processes change our understanding of extreme galactic environments? We still lack a connection between these small scale observations of the Milky Way's CMZ and the large scale models which describe the cycles and evolution of mass inflows and outflows in galaxy centers. I have developed new zoom-in simulations of a Milky Way-like CMZ to provide a physically complex apples-to-apples comparison of CMZ gas dynamics and star formation for large surveys.