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

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 $\sim 0.05$ parsec of Sgr A* in the plane of the sky, moving with blue-shifted radial velocities $\gtrsim 600$ km/s. Fine structure line measurements spanning ionization energies $\sim 7-55$ 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 metallicity is $\sim 1-2.5Z_{\text{sun}}$, with a Wolf-Rayet star-driven ionizing radiation field, and significant nickel and iron dust destruction. Increased flux at energies $\gtrsim 41$ eV suggests that the compact gas structures experience an additional harder ionizing radiation source, which is most likely driven by localized fast radiative shocks from stellar winds, a hypothetical Sgr A* outflow, and/or interactions with the ambient medium.