Cold gas in the Milky Way's nuclear wind

Abstract

The centre of the Milky Way is the site of several high-energy processes that have strongly impacted the inner regions of our Galaxy. Activity from the super-massive black hole, Sgr A*, and/or stellar feedback from the inner molecular ring expel matter and energy from the disc in the form of a galactic wind. Multiphase gas has been observed within this outflow, from hot highly-ionized, to warm ionized and cool atomic gas. To date, however, there has been no evidence of the cold and dense molecular phase. Here we report the first detection of molecular gas outflowing from the centre of our Galaxy. This cold material is associated with atomic hydrogen clouds travelling in the nuclear wind. The morphology and the kinematics of the molecular gas, resolved on ~1 pc scale, indicate that these clouds are mixing with the warmer medium and are possibly being disrupted. The data also suggest that the mass of molecular gas driven out is not negligible and could impact the rate of star formation in the central regions. The presence of this cold, dense, high-velocity gas is puzzling, as neither Sgr A* at its current level of activity, nor star formation in the inner Galaxy seem viable sources for this material.

Published in the August 19 issue of Nature. This is the authors' version before final edits. Published version is available at http://www.nature.com/articles/s41586-020-2595-z

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Cited by in corpus (10)

• The 1.28 GHz MeerKAT Galactic Center Mosaic
• The Galactic center chimneys: The base of the multiphase outflow of the Milky Way
• Intermediate- and high-velocity clouds in the Milky Way II: evidence for a Galactic fountain with collimated outflows and diffuse inflows
• Molecular gas distribution perpendicular to the Galactic plane
• First Co-spatial Comparison of Stellar, Neutral-, and Ionized-gas Metallicities in a metal-rich galaxy: M83
• Molecular Gas within the Milky Way's Nuclear Wind
• AGN-driven galactic outflows: comparing models to observations
• Diverse metallicities of Fermi bubble clouds indicate dual origins in the disk and halo
• CO Emission Delineating the Interface between the Milky Way Nuclear Wind Cavity and the Gaseous Disk
• A Near-Infrared Search for Molecular Gas in the Fermi Bubbles