2026 workshop program
Ingredients of Our Black Hole's Diet: Using Unsupervised Learning to Correlate Different Gas Phases in the Center of the Milky Way
The work
Abstract
At the center of our Milky Way sits Sagittarius A* (Sgr A), a supermassive black hole four million times the mass of our Sun, and our closest cosmic laboratory for understanding how black holes grow and the fate of our galaxy. Despite the Galactic Center being the best studied region around any supermassive black hole, we still don’t fully understand the mechanics and composition of gas that ends up feeding Sgr A versus being pushed away from it—a gap that limits our understanding of black hole growth across the universe. Using radio telescope observations from the Atacama Large Millimeter/submillimeter Array (ALMA) and machine learning techniques, we map two distinct phases of gas near Sgr A* (inner ~ 1pc), cold molecular gas and hot ionized hydrogen. We use principal component analysis tomography to isolate dominant signals in the complex combined three-dimensional position-position-velocity data and Gaussian mixture modeling to statistically group gas structures by their properties. We identify several distinct gas structures near Sgr A* composed of both molecular and ionized gas, including bow shocks, expanding shells, comet-like clouds, and potential molecular rain cloudlets, each shedding light on a different stage of black hole activity. This work is ongoing, and our continued analysis aims at understanding how these structures connect to the cycle of black hole feeding and feedback in our Galaxy.