MHD Simulations of Strongly Magnetized H ii Region Evolution: Evidence for Ionized Gas Filamentation

Journal article

Recent James Webb Space Telescope observations of H ii regions in the Central Molecular Zone (CMZ) have shown a highly filamentary morphology distinct from H ii regions in other parts of the Galaxy. We present magnetohydrodynamic (MHD) simulations of strongly magnetized (plasma-β ≪ 1) H ii region evolution that investigate and describe the formation of these ionized gas filaments. H ii region evolution has been simulated in a 30 pc3 box, in distinct models with preplaced overdensities in the ambient medium and overdensities that have been generated with driven turbulence. We find that when these overdensities are seeded in the ambient medium before the birth of the ionizing source, the photoionized plasma stripped off of these dense blobs is funneled into long filaments along the magnetic field lines. The length and emission measure of these ionized gas filaments are similar to the filaments observed in the CMZ. Given that these filaments are effectively magnetically confined flows of photoionized gas, their density and curvature are influenced by the density of the blob and the geometry of the configuration.

Authors: Crowe, S; Tu, Y; Li, Z; Kim, J; Bally, J

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: The Astrophysical Journal
• Volume: 1000
• Issue: 2
• Pages: 206
• Article number: 206
• Publication date: 2026-03-24
• Acceptance date: 2026-02-24
• DOI: 10.3847/1538-4357/ae4bd7
• EISSN: 1538-4357
• ISSN: 0004637X, 0004-637X
• Language: English
• Keywords: Interstellar medium; Galactic center; Radiative magnetohydrodynamics; Interstellar filaments; Magnetohydrodynamical simulations; Star formation; H II regions; Photoionization