Of galactic magnetism

The origin of magnetic fields associated with galaxies is still a matter
of debate. One theory attributes it to
a dynamo-like mechanism in rhe
galaxies, while the other contends
that the dynamo is long dead and
the magnetic field is constant. Both
the theories are based on magneto-hydrodynamics which says that
magnetic field is frozen into the
interstellar gas.

Researchers have recently
reported the existence of magnetic
spiral arms in the galaxy NGC6946,
This finding could have major
implications on the understanding
of the mechanism responsible for
the magnetic field, since it is difficult to explain a pure magnetohydrodynamic origin of such an effect.