Gravity seminar - Jerome Guilet Seminar

 

Extremely strong magnetic fields of the order of 10^15 Gauss are required to explain the properties of magnetars, the most magnetic neutron stars. Such a strong magnetic field is expected to play an important role for the dynamics of core-collapse supernovae, and in the presence of rapid rotation may power the most energetic supernovae (hypernovae, superluminous supernovae) and long gamma-ray bursts. The origin of these strong magnetic fields remains, however, obscure and most likely requires an amplification over many orders of magnitude in the protoneutron star. One of the most promising agents is the magneto-rotational instability (MRI), which can in principle amplify exponentially a weak initial magnetic field to a dynamically relevant strength. I will describe our current understanding of the MRI in protoneutron stars, how it differs to the mostly studied context of accretion disks, and show recent results on the impact of physical conditions specific to protoneutron stars such as neutrino radiation, strong buoyancy effects and large magnetic Prandtl number.