We performed 2D, axisymmetric, MHD simulations with Cosmos++ in order to
examine the growth of the magnetorotational instability (MRI) in core--collapse
supernovae. We have initialized a non--rotating 15 solar mass progenitor,
infused with differential rotation and poloidal magnetic fields. The collapse
of the iron core is simulated with the Shen EOS, and the parametric Ye and
entropy evolution. The wavelength of the unstable mode in the post--collapse
environment is expected to be only ~ 200 m. In order to achieve the fine
spatial resolution requirement, we employed remapping technique after the iron
core has collapsed and bounced.
The MRI unstable region appears near the equator and angular momentum and
entropy are transported outward. Higher resolution remap run display more
vigorous overturns and stronger transport of angular momentum and entropy. Our
results are in agreement with the earlier work by Akiyama et al. (2003) and
Obergaulinger et al. (2009).Comment: 3 pages, 2 figures. To appear in the proceedings of the "Deciphering
the Ancient Universe with Gamma-Ray Bursts", April 2010, Kyoto, Japan, eds.
N. Kawai and S. Nagataki (AIP
