Thin accretion disks are stabilized by a strong magnetic field

Understand

By studying three-dimensional, radiative, global simulations of sub-Eddington, geometrically thin black hole accretion flows we show that thin disks which are dominated by magnetic pressure are stable against thermal instability.

• Such disks are thicker than predicted by the standard model and show significant amount of dissipation inside the marginally stable orbit.
• Radiation released in this region, however, does not escape to infinity but is advected into the black hole.
• We find that the resulting accretion efficiency ($5.5\pm0.5\%$ for the simulated $0.8\dot M_{\rm Edd}$ disk) is very close to the predicted by the standard model ($5.7\%$).