Bulk viscosity of magnetized neutron star matter

We study the effect of a magnetic field on the bulk viscosity of nuclear matter in neutron stars. We employ the framework of relativistic mean-field theory to model the dense nuclear matter in neutron stars. The effects are first studied for the case when the magnetic field does not exceed the critical value to confine the electrons to the lowest Landau levels. We then consider the case of an intense magnetic field to evaluate the viscosity for the URCA processes and show that the inequality pF(e) + pF(p) ≥ pF(n) is no longer required to be satisfied for the URCA processes to proceed. (author)