A few nice magnetic field energy density powerplan I discovered:
Neutron Star Merger Simulation
Image by NASAblueshift
These pictures display the merger of two neutron stars just lately simulated making use of a new supercomputer model. Redder colors indicate reduce densities. Green and white ribbons and lines represent magnetic fields. The orbiting neutron stars quickly shed energy by emitting gravitational waves and merge immediately after about three orbits, or in less than 8 milliseconds.