Numerical simulations of the magnetorotational instability in protoneutron stars: I. Influence of buoyancy

Understand

The magneto-rotational instability (MRI) is considered to be a promising mechanism to amplify the magnetic field in fast rotating protoneutron stars.

• In contrast to accretion disks, radial buoyancy driven by entropy and lepton fraction gradients is expected to have a dynamical role as important as rotation and shear.
• We investigate the poorly known impact of buoyancy on the non-linear phase of the MRI, by means of three dimensional numerical simulations of a local model in the equatorial plane of a protoneutron star.
• The use of the Boussinesq approximation allows us to utilise a shearing box model with clean shearing periodic boundary conditions, while taking into account the buoyancy driven by radial entropy and composition gradients.