Simulations show magnetic fields destabilize low-shear disc regions to form filaments via magneto-Jeans mechanism

The study initializes equilibrium discs and varies initial magnetisation while holding other parameters fixed. Filament formation is tracked via surface-density maps and Fourier analysis of non-axisymmetric structures. Strong fields suppress axisymmetric Jeans modes yet promote non-axisymmetric feathers when shear is weak, reversing the usual stabilising role of magnetic tension.

This reversal matters for dwarf galaxies whose slowly rising rotation curves keep shear low across most of the disc. The result supplies a physical route to the filamentary HI and molecular structures observed in systems such as the Magellanic Clouds and many low-mass spirals, where pure hydrodynamic models under-predict arm spacing.

Prior analytic work on the magneto-Jeans instability (e.g., Elmegreen 1994; Kim & Ostriker 2002) is now directly tested in global, self-gravitating discs. Future zoom-in cosmological runs that include resolved magnetic fields can test whether the same low-β, low-shear conditions dominate at high redshift.

The chief limitation is the ideal-MHD assumption and fixed supernova feedback; non-ideal effects and stellar feedback could saturate the instability at different amplitudes.