A semianalytic model for cyclotron line formation

We present here a semi-analytic, physically motivated model for the formation of the cyclotron first harmonic line, as well as higher harmonic lines. The model is based upon three basic physical principles: (1) the radiative transfer is a smooth stochastic process, (2) the first harmonic feature forms from complete redistribution in a single block of resonant photon scatters, and (3) the higher harmonics are well-approximated as true absorption features. The emergent spectral shapes are expressed as quadratures. This model includes the essential relativistic effects and is valid for weak fields (BB c =4.414×10 13 G) in static media where the first harmonic is optically thick in the line core but not in its wings