The Local Stability of Magnetized Rotating Plasmas with Superthermal Fields
Martin Pessah ( The University of Arizona) - Tuesday May 11 at 12:00 noon
During the last decade it has become evident that the magnetorotational
instability is at the heart of the enhanced angular momentum transport in
weakly magnetized accretion disks around neutron stars and black holes. I
will talk about the local linear stability of differentially
rotating, magnetized flows and the evolution of the magnetorotational
instability beyond the weak-field limit. I will show that the presence of
an azimuthal component in the magnetic field plays a crucial role not only
in the growth rates of the unstable modes but also in determining which
modes are subject to instabilities. We will see that, when superthermal
toroidal fields are considered in local stability analyse of cylindrically
rotating plasmas, both compressibility and magnetic tension terms,
originated by the curvature of toroidal field lines, should be taken fully
into account. For a quite broad range of magnetic field strengths, two
distinct instabilities are present. These results have broad applicability
to the evolution of magnetohydrodynamic instabilities in settings such as
the inner regions of accretion disk around magnetic neutron stars, the
rarefied hot coronae of accretion disks, and in boundary layers, where
strong toroidal fields can be generated by shear.
The seminar will be held in 501 Campbell Hall.
Return to seminar schedule