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1 Introduction to the Pulsars
Obviously, most of pulsars have extremely strong magnetic fields. The charged
particles will obtain very high speeds as they motion along the magnetic field lines
in the extremely strong magnetic fields. Since the curvatures are usually very great
around the magnetic poles in the extremely strong magnetic fields, the charged
particles with high speeds are accelerated again, and thus the curvature radiations
produced. The very strong electromagnetic waves will be emitted by the curvature
radiation mechanism, where the electromagnetic waves in each frequency band,
including the radio and X-ray bands, will together form a radiation cone with special
directionality near the magnetic poles and radiate energy toward space.
1.4.2.2 Synchrotron Radiation
Synchrotron radiation is the electromagnetic radiation emitted when the relativistic
electrons are accelerated radially by the Lorentz force in magnetic fields. In other
words, the electrons are subject to an acceleration perpendicular to their velocities.
The synchrotron radiation was first observed from a General Electric synchrotron
accelerator built in 1946 and announced in 1947, and then also named sync-radiation.
The electrons from the sync-radiation generally make circular or spiral motions.
It is well known that a rotating magnetic field can produce an electric field. The
rotating neutron stars with ultra-strong magnetic fields can produce the electric field
strengths of above 10
14 V/m on their surfaces. For so strong electric fields, it is enough
to overcome the force of gravity, and thus all electrons and protons will be pulled
out to form the plasmas around the neutron stars. The plasmas are controlled by
the ultra-strong magnetic fields, and they revolve together with magnetic induction
lines around the rotation axes of neutron stars. The rotational linear velocities are
proportional to the distances away from the neutron stars. Supposed that the rotation
velocities of the charged particles get to the light velocity c at distance r c , then a
cylinder with the magnetic axis of neutron star as the central axis and with r c as
the radius will be formed, and usually called light-velocity cylinder. For the Crab
Pulsar, the radius of its light-velocity cylinder is about 1600 km.
Outside the light-velocity cylinder, the charged particles are constrained no longer
by the magnetic field of neutron star; they will escape rapidly from the neutron
star and become a possible source of cosmic rays. In the region where the lightvelocity cylinder intersects with the magnetic equator of neutron star, the highly rapid
electrons make the spiral orbit motions around the magnetic field lines, and thus a
beam of sync-radiation will be emitted in their motion direction. If the sync-radiation
beams sweep across nearby the Earth, the pulsating signals from the neutron stars
will be produced. Whether the sync-radiation beams are emitted along the magnetic
axes or along the magnetic equators at the light-velocity cylinders, it is an important
prerequisite to suppose that the magnetic axes of neutron stars are not parallel to
their rotation axes. In other words, only if there is an angle between the magnet axis
of neutron star and its rotation axis, the pulsating signals will be produced and the
lighthouse effect formed.
1 Introduction to the Pulsars
Obviously, most of pulsars have extremely strong magnetic fields. The charged
particles will obtain very high speeds as they motion along the magnetic field lines
in the extremely strong magnetic fields. Since the curvatures are usually very great
around the magnetic poles in the extremely strong magnetic fields, the charged
particles with high speeds are accelerated again, and thus the curvature radiations
produced. The very strong electromagnetic waves will be emitted by the curvature
radiation mechanism, where the electromagnetic waves in each frequency band,
including the radio and X-ray bands, will together form a radiation cone with special
directionality near the magnetic poles and radiate energy toward space.
1.4.2.2 Synchrotron Radiation
Synchrotron radiation is the electromagnetic radiation emitted when the relativistic
electrons are accelerated radially by the Lorentz force in magnetic fields. In other
words, the electrons are subject to an acceleration perpendicular to their velocities.
The synchrotron radiation was first observed from a General Electric synchrotron
accelerator built in 1946 and announced in 1947, and then also named sync-radiation.
The electrons from the sync-radiation generally make circular or spiral motions.
It is well known that a rotating magnetic field can produce an electric field. The
rotating neutron stars with ultra-strong magnetic fields can produce the electric field
strengths of above 10
14 V/m on their surfaces. For so strong electric fields, it is enough
to overcome the force of gravity, and thus all electrons and protons will be pulled
out to form the plasmas around the neutron stars. The plasmas are controlled by
the ultra-strong magnetic fields, and they revolve together with magnetic induction
lines around the rotation axes of neutron stars. The rotational linear velocities are
proportional to the distances away from the neutron stars. Supposed that the rotation
velocities of the charged particles get to the light velocity c at distance r c , then a
cylinder with the magnetic axis of neutron star as the central axis and with r c as
the radius will be formed, and usually called light-velocity cylinder. For the Crab
Pulsar, the radius of its light-velocity cylinder is about 1600 km.
Outside the light-velocity cylinder, the charged particles are constrained no longer
by the magnetic field of neutron star; they will escape rapidly from the neutron
star and become a possible source of cosmic rays. In the region where the lightvelocity cylinder intersects with the magnetic equator of neutron star, the highly rapid
electrons make the spiral orbit motions around the magnetic field lines, and thus a
beam of sync-radiation will be emitted in their motion direction. If the sync-radiation
beams sweep across nearby the Earth, the pulsating signals from the neutron stars
will be produced. Whether the sync-radiation beams are emitted along the magnetic
axes or along the magnetic equators at the light-velocity cylinders, it is an important
prerequisite to suppose that the magnetic axes of neutron stars are not parallel to
their rotation axes. In other words, only if there is an angle between the magnet axis
of neutron star and its rotation axis, the pulsating signals will be produced and the
lighthouse effect formed.