The Central Molecular Zone (CMZ) is a key region at the center of the Milky Way, where gas flows toward the galaxy’s core. Scientists are still trying to understand its 3D structure, how stars form there, and how it controls this gas movement.
Studying the CMZ is difficult because we don’t have a clear, top-down view of the Milky Way. To tackle this, researchers at UConn’s Milky Way Laboratory, led by Professor Cara Battersby, have created a detailed 3D model, which they present in a series of papers in the Astrophysical Journal.
Professor Cara Battersby describes the Central Molecular Zone (CMZ) as the galaxy’s “way station,” where gas flows from the Milky Way’s disk along dust lanes. Some of this gas stays in the CMZ, orbiting the center and forming stars, while others continue toward the supermassive black hole at the galaxy’s core.
Professor Battersby is investigating when the Milky Way’s supermassive black hole, Sagittarius A, actively pulls in material. The CMZ plays a key role in regulating this gas flow, but studying it is not easy because we can only see it from the side.
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To better understand how the CMZ controls this process, Battersby’s team creates a detailed 3D model using extensive data on regional gas clouds. Their work aims to provide a top-down view, helping scientists determine which clouds are moving toward the black hole and which are simply orbiting.
Researchers first created a detailed catalog of structures in the Central Molecular Zone (CMZ), measuring key properties like mass, temperature, and velocity. The next phase focused on smaller structures, believed to be molecular clouds where stars may form.
Two papers explored these clouds in depth—one led by former postdoctoral fellow Daniel Walker and another by Ph.D. student Dani Lipman.
Since the galactic center emits light across many wavelengths, scientists used various methods to determine which clouds are in front of or behind, helping map the region more accurately.
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Stars form in dense, cold molecular clouds, but most of the gas in the galactic center is hot and spread out. When these cooler clouds are in front of the galactic center, they block its bright light and appear as shadows. The light passes through if they are behind it, making them invisible.
Researchers developed methods to measure how much light is blocked to determine a cloud’s position. One study examined radio wavelengths, tracking how clouds absorb radio signals. Another study focused on infrared dust extinction, analyzing shadows to estimate whether a cloud is in front of or behind the galactic center.
Researchers modeled the Central Molecular Zone (CMZ) based on their data and compared it to existing top-down models of the Milky Way’s center. They found that previous models lacked complexity, particularly in tracking the movement of molecular clouds.
They introduced a new ellipse model to improve this and are now working on a more refined best-fit model. This updated version will incorporate new data and be publicly available, allowing future scientists to refine it further.
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Understanding the CMZ’s 3D structure is crucial for studying extreme cosmic events, such as gas flows toward the Milky Way’s supermassive black hole and star formation in turbulent environments. By mapping the CMZ more accurately, researchers can better explore these dynamic processes.
Journal References:
Authors: Cara Battersby, Daniel L. Walker, Ashley Barnes, Adam Ginsburg, Dani Lipman, Danya Alboslani, H Perry Hatchfield, John Bally, Simon C. O. Glover, Jonathan D. Henshaw, Katharina Immer, Ralf S. Klessen, Steven N. Longmore, Elisabeth A. C. Mills, Sergio Molinari, Rowan Smith, Mattia C. Sormani, Robin G. Tress, and Qizhou Zhang.
Journal: The Astrophysical Journal
- 3D CMZ. I. Central Molecular Zone Overview. DOI 10.3847/1538-4357/adb5f0
- 3D CMZ. II. Hierarchical Structure Analysis of the Central Molecular Zone. DOI 10.3847/1538-4357/adb844
- 3D CMZ. III. Constraining the 3D Structure of the Central Molecular Zone via Molecular Line Emission and Absorption. DOI 10.3847/1538-4357/adb5ef
- 3D CMZ. IV. Distinguishing Near versus Far Distances in the Galactic Center Using Spitzer and Herschel. DOI 10.3847/1538-4357/adb5ee
