Radiative transfer in a strongly magnetized plasma. II. Effects of comptonization

We present results of numerical calculations of radiative transfer in hot, strongly magnetized plasma, including Comptonization and redistribution of photons in the cyclotron line. Polarization, angle, and frequency dependent differential scattering cross sections were obtained in the nonrelativistic approximation. An approximate, two-stream transfer equation was solved for homogeneous radiating slabs of various optical depths using Feautrier's method. For intermediate optical depths (slab transparent in the wings of the line) we obtained the asymmetric, self-reversed emission line recently predicted by Wasserman and Salpeter. However, the line shape can be changed significantly due to the presence of ordinary photons, which have weaker resonances in their cross sections. For very large optical depths we find an absorption line superposed ont he usual Wien continuum. We conclude that the cyclotron line in the Her X-1 spectrum is more likely to be an absorption line than an emission line