Ionization Structure and Metal Enrichment of the Galactic Center Minispiral Observed with JWST

Nicole M Ford; Mayura Balakrishnan; Sebastiano D. von Fellenberg; Daryl Haggard; Joseph M. Michail; Yuzhu Cui; Joseph L. Hora; Joey Neilsen; Giacomo Principe; Tamojeet Roychowdhury; Nadeen B Sabha; Howard A. Smith; Zach Sumners; S. P. Willner

arXiv · 2605.13995

Ionization Structure and Metal Enrichment of the Galactic Center Minispiral Observed with JWST

Nicole M Ford·Mayura Balakrishnan·Sebastiano D. von Fellenberg·Daryl Haggard·Joseph M. Michail·Yuzhu Cui·Joseph L. Hora·Joey Neilsen·Giacomo Principe·Tamojeet Roychowdhury·Nadeen B Sabha·Howard A. Smith·Zach Sumners·S. P. Willner

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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 MRS instrument to disentangle mid-infrared ionized gas structures in the central 0.1 parsec of the Galaxy. The Galactic Minispiral's Bar and Northern Arm are revealed by their distinct morphological and kinematic signatures. Several compact (<1 arcsec) gas structures including X7 also appear within ~0.05 parsec of Sgr A* in the plane of the sky, moving with blue-shifted radial velocities >~600 km/s. 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/destruction for each identified gas structure. Overall, the Minispiral gas shows mildly super-solar 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.

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Nicole M Ford, Mayura Balakrishnan, Sebastiano D. von Fellenberg, Daryl Haggard, Joseph M. Michail, Yuzhu Cui, Joseph L. Hora, Joey Neilsen, Giacomo Principe, Tamojeet Roychowdhury, Nadeen B Sabha, Howard A. Smith, Zach Sumners, S. P. Willner. 2026-05-13. Ionization Structure and Metal Enrichment of the Galactic Center Minispiral Observed with JWST. https://arxiv.org/abs/2605.13995

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