Magnetic pressure support in sub-Eddington AGN disks suppresses predicted Lyman edge at 13.6 eV

The restarted multi-frequency run computes emergent continuum directly from angle-dependent radiation fluxes. Surface densities fall below 10^3 g cm^-2 across the simulated domain, weakening the Lyman opacity jump that classical radiation-pressure-supported atmospheres predict. No discontinuity appears at 13.6 eV; instead the spectrum remains smooth through the UV.

Standard thin-disk theory assumes radiation pressure dominates vertical support and produces a prominent edge. Here magnetic pressure provides most of the vertical force, dropping density enough that bound-free opacity no longer jumps sharply. This matches the long-standing observational absence of a Lyman edge in AGN UV continua reported by HST and IUE.

Emission near 13.6 eV is still expected to arise partly inside the simulation's inner boundary, so the result remains provisional. Extension to smaller radii, non-LTE transfer, and a wider Eddington-ratio grid are required before the model can be compared quantitatively with specific quasar spectra.

The work demonstrates how global 3D MHD simulations can directly test spectral predictions that one-zone models cannot address, tightening the link between disk dynamics and observed continua.