Cyclotron harmonics in accreting pulsars and gamma-ray bursters - Effect of two-photon processes

Abstract

The radiative transfer at the cyclotron first, second,and third harmonics is discussed for simplified accreting pulsarand gamma-ray burster emission regions. Two-photon scattering aswell as two-photon emission, which play a major role in determiningthe line-strength ratio is included. Stimulated effects are alsoimportant for accurately modeling the optically thick line and continuumregions. These calculations are compared with recent observations ofaccreting pulsars and gamma-ray burst sources, showing a qualitativeagreement. The cyclotron harmonic lines should be strongly polarized.