The Lighthouse Model (2) ...
It is a basic principle of physics that a magnetic field varying in time produces an
electrical field.
Thus, the rapidly spinning magnetic field generates a very strong electrical
field around the neutron star.
The Lighthouse Mechanism
This field accelerates electrons away from the surface at
"hot spots" near the magnetic poles
and these accelerated electrons produce radiation by the
synchrotron effect (which was discussed in Chapter 5).
Because of the synchrotron mechanism and the high velocity of the particles,
the radiation produced is beamed strongly in the direction of
electron motion. These beams of radiation rotate with the star, but since the magnetic axis does not
generally coincide with the rotation axis (recall, for example,
that Earth's rotation and magnetic axes have different orientations),
the beams rotate in a kind of corkscrew fashion.
If these gyrating beams
sweep over the Earth, they act similar to a lighthouse and we observe flashes of light. Thus, the star
appears to be pulsing, even though it is neither pulsing nor is it
really a star.
The basic idea of the lighthouse model is
illustrated in the above animation.
