Speaker
Description
Neutron stars have the strongest magnetic fields in the universe, with fields up to 10^15 G in so-called magnetars. At such field strengths the classical Hall effect becomes one of the dominant effects governing the evolution of the magnetic fields. One interesting aspect of the Hall effect is that it depends on the sign of the field, unlike virtually all of classical MHD, where the sign of B is not important. Another interesting feature -- which also makes the problem numerically challenging -- is the fact that the nonlinear Hall term has just as many derivatives as the linear Ohmic decay term, meaning that there is no guarantee that any dissipative cutoff regime exists at all.
In this talk I will summarise over a decade's worth of numerical work -- starting with a collaboration with Günther Rüdiger in 2002 -- exploring some of these issues in Hall MHD, and comparing results also with real neutron stars. I will also show how the basic Hall MHD can be extended to include a temperature equation as well, with the evolution of magnetic field B and temperature T coupled together.
