On the force-free magnetosphere of aligned rotator

We investigate in details properties of stationary force-free magnetosphere of aligned rotator assuming the last closed field line lying in equatorial plane at large distances from pulsar. The pulsar equations is solved numerically using multigrid code with high numerical resolution, physical properties of the magnetosphere are obtained with high accuracy. We found a set of solutions with different sizes of the closed magnetic field line zone and verify the applicability of the force-free approximation. We discuss the role of electron-positron cascades in supporting of the force-free magnetosphere and argue that the closed field line zone should grow with time slower than the light cylinder. This yield the pulsar breaking index less than 3. It is shown, that models of aligned rotator magnetosphere with widely accepted configuration of magnetic field, like one considered in this paper, have serious difficulties. We discuss solutions of this problem and argue that in any case pulsar energy losses should evolve with time differently than predicted by the magnetodipolar formula.