Pulsar Mechanics
pulsars are non-aligned rotating magnets
induced electric
fields
(producing by time varying magnetic fields: Faraday's law)
produce electric
forces
strong enough
to rip electrons off
the neutron star surface
surrounding the
neutron
star is a conducting plasma (magnetosphere)
dominated by
electromagnetic
forces (not gravitational)
inside the light
cylinder
(co-rotation radius ~ c P/2p),
the plasma is frozen
into the magnetic field lines...
the whole mess
rotates
as a solid body
inside light
cylinder,
B lines are closed,
and therefore
electrons
(or positrons) spiral around the
magnetic field lines
back and forth from pole to pole
these electrons,
accelerated
by induced emf,
produce the
relativistic
synchrotron radiation
that seems to fill
the interior of the supernova remnant...
these relativistic
electrons can emit g
rays energetic enough
to pair produce (
g + g
--> e - + e+ ) more charged particle
pairs
that are accelerated etc etc
but outside the
light
cylinder, the B lines must be open-ended,
leaking out into
space:
particles spiral
along
the lines that are densest near
(and parallel to)
the magnetic poles;
these
synchrotron-emitting
electrons strongly beam
their radiation
along
the poles
producing the
pulsar's
lighthouse effect
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1500 km (light cylinder) |
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(Faraday's law: DF/Dt = B(pR2)/P ~ emf) |
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