Scattering of light in a strongly magnetized plasma

Abstract

The Thomson cross section in a strongly magnetized electron plasma is reexamined with a view to extending previous results of Canuto, Lodenquai, and Ruderman beyond the cold-plasma limit. To this end a formal relation is established between the differential photon cross section and the polarization currents induced in the medium by the incident photon. In the cold-plasma limit our formal approach leads to a substantially simplified differential cross section allowing an intuitive understanding of the scattering mechanism and the resulting anisotropy. For the integrated partial and total (summed over final polarizations) cross sections we recover previous results. The structure of this theory at and near the cyclotron resonance is examined including the necessary dissipative and broadening mechanisms. Extensions beyond the cold-plasma limit are discussed for the application to the problem of the accreting x-ray pulsars. Under conditions typical of the accretion column of some x-ray pulsars it is expected that the birefringent properties of the vacuum may significantly alter both the photon cross sections and the polarization properties of the radiation.