Influence of magnetorotational instability on neutrino heating: A new mechanism for weakly magnetized core-collapse supernovae

We investigated the impact of magnetorotational instability (MRI) on the dynamics of weakly magnetized, rapidly rotating core-collapse supernovae by conducting high-resolution axisymmetric MHD simulations with simplified neutrino transfer. We found that an initially sub-magnetar-class magnetic field is drastically amplified by MRI and substantially affects the dynamics thereafter. Although the magnetic pressure is not strong enough to eject matter, the amplified magnetic field efficiently transfers angular momentum from small to large radii and from higher to lower latitudes, which causes the expansion of the heating region due to the extra centrifugal force. This then enhances the efficiency of neutrino heating and eventually leads to neutrino-driven explosion. This is a new scenario of core-collapse supernovae that has never been demonstrated by past numerical simulations.