Radiative transfer with Compton scattering in spherically symmetric shells

Abstract

The radiative transfer equation with Compton scattering is solved for spherically symmetric shells. The purpose of the study is to determine how gamma rays or X-rays change their energies and how they become reflected and transmitted due to Compton scattering in the spherical shells of the outer layers of stars. The following assumptions are made: (1) the medium is divided into spherical shells, each having equal optical thickness, (2) the electron motion is either neglected, or else the electron kinetic energy is much less than the photon energy, (3) isotropic scattering, and (4) the photon-energy dependence on the scattering cross section is neglected. It is found that multiple Compton scattering redistributes the initial energy over a range of 1 to 10 Compton wavelengths. A good fraction of the incident radiation is transferred across the shell. This fraction is redistributed in terms of wavelength, and its percentage is dependent on the optical thickness of the medium.