The Thomson scattering is the elastic dispersion of electromagnetic radiation through a free charged particle, as described by the electrodynamics. At the Thomson scattering, the kinetic energy of the particle and the energy of the photon remain constant. It is the limit of Compton scattering for low energy. This limit remains valid as long as the photon's energy is much smaller than the mass energy of the particle.
In the case of Thomson scattering, a charged particle is accelerated by an incoming wave, which in turn sends the particle radiation with the same energy. Thus, the incoming wave is scattered. The phenomenon was first explained by physicist Joseph John Thomson.
As long as the particle goes a lot slower than the light speed (and the movement is not relativistic), the acceleration of the particle is mainly determined by the electrical component of the input wave and the magnetic component can be neglected. The particle will then move toward the oscillatory electric field resulting in electromagnetic dipole radiation. The moving particle radiates strongly in the direction perpendicular to its motion and the radiation will be polarized in its direction of movement. The scattered light may therefore be more or less polarized, depending on the direction from which an observer observes the scattering.
wiki
