Ionization Structure and Metal Enrichment of the Galactic Center Minispiral Observed with JWST
Year: 2026
Type: article
Abstract: Sagittarius A* (Sgr A*) is the nearest quiescent supermassive black hole, and its proximity offers a unique opportunity to study its surrounding fuel supply. We leverage extensive spatial and spectroscopic information provided by the JWST/MIRI Medium Resolution Spectrograph instrument to disentangle mid-infrared ionized gas structures in the central 0.1 pc of the Galaxy. The Galactic Minispiral’s Bar and Northern Arm are revealed by their distinct morphological and kinematic signatures. Several compact (<1″) gas structures including X7 also appear within ∼0.05 pc of Sgr A* in the plane of the sky, moving with blueshifted radial velocities ≳ 600 km s −1 . Fine-structure line measurements spanning ionization potentials ∼ 7–55 eV are used to constrain the incident radiation field, metal abundances (neon, argon, sulfur, nickel, and iron), and dust depletion or destruction for each identified gas structure. Overall, the Minispiral gas shows mildly supersolar abundances (∼1.8 × solar), a Wolf–Rayet-star-driven radiation field consistent with ionization parameters spanning − 1.6 ≲ log U ≲ − 0.6 , and significant nickel and iron dust destruction. In particular, the enhanced ionization state and strong dust processing in the high-velocity compact gas structures suggest that these features may experience localized fast shocks.
Source: The Astronomical Journal
Institutions: McGill University, University of Toronto, Max Planck Institute for Radio Astronomy, Center for Astrophysics Harvard & Smithsonian, Central China Normal University, Villanova University, University of Trieste, Istituto Nazionale di Fisica Nucleare, Istituto di Radioastronomia di Bologna, National Institute for Astrophysics, University of California, Berkeley, Universität Innsbruck
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Funders: National Science Foundation, National Aeronautics and Space Administration, Alexander von Humboldt-Stiftung, McGill University, Space Telescope Science Institute, Deutscher Akademischer Austauschdienst, Canada Research Chairs, Canadian Space Agency, Canadian Institutes of Health Research, Natural Sciences and Engineering Research Council of Canada, Fonds de recherche du Québec – Nature et technologies
OpenAlex ID: W7161284863