  We investigated the impacts of magnetorotational instability (MRI) on the
dynamics of weakly magnetized, rapidly rotating core-collapse by conducting
high resolution MHD simulations in axisymmetry 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 higher to
lower latitudes, which causes the expansion of the heating region at low
latitudes due to the extra centrifugal force. This then enhance 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
numerical simulations so far.
