An international research team led by Michael Kramer and Kuo Liu from the Max Planck Institute for Radio Astronomy in Bonn, Germany, have studied magnetars to uncover an underlying law that appears to apply universally to neutron stars.
they said that it shows the emission of electromagnetic energy has the same cause, but didn't explain what that cause is...
they said that magnetars don't emit energy all the time, so we had to catch them when they did emit: that is false: we have to catch them when they're emitting at us, which is a very-different frame-of-reference.
Also, if the things are neutron-stars, then how the hell can they even have any electromagnetic field?
Neutrons are neutral.
It must be a crust of non-neutron protons & electrons, or the plasma swirling in, or something, that's producing the electromagnetic field...
No need to bother commenting on anything I say:
just random thoughs flitting through a deteriorating old brain...
Your last one is a good question. I don't have an answer but I was leaning towards some sort of conservation law (e.g. normal stars have magnetic fields, when they get squeezed down to a neutron star those fields must go somewhere and it will be very much "concentrated"). Apparently this is a bit too easy (didn't expect to be nothing different). Wikipedia provides a reference to a not too recent (2003) survey, namely this one: https://arxiv.org/abs/astro-ph/0307133 . I don't know if it's the state of the art but it surely is interesting.