  Combining resolved spectroscopy with deep imaging, XMM-Newton is providing
new insights on the particle acceleration processes long known to be at work in
the magnetospheres of isolated neutron stars. According to a standard
theoretical interpretation, in neutron stars' magnetospheres particles are
accelerated along the B field lines and, depending on their charge, they can
either move outward, to propagate in space, or be funnelled back, towards the
star surface. While particles impinging on the neutron star surface should heat
it at well defined spots, outgoing ones could radiate extended features in the
neutron star surroundings. By detecting hot spots, seen to come in and out of
sight as the star rotates, as well as extended features trailing neutron stars
as they move in the interstellar medium, XMM-Newton provides the first
end-to-end test to the particle acceleration process.
