Vertical Structure of Pulsar Magnetospheres
Soon after discovery of the first pulsar it was found that average profiles, obtained by integrating many single pulses synchronously with the period of the pulsar, depend strongly on the observing frequency. This effect is known as Radius-to-Frequency Mapping (RFM). The simplest and elegant explanation is that higher frequencies are generated in the narrow part of the emission cone, closer to the surface of the star, and lower frequencies are produced in the wider part of the cone, which is further away from the star. Results obtained by most authors indicate that emission altitudes are not more than 20% of the light cylinder radius. While all researchers agree that RFM generally is working, it is not quite clear how thick a layer producing one radio frequency may be, and if it is possible that two or more radio frequencies, different by possibly several hundred MHz could originate from the same layer of the magnetosphere. One of the goals of this project is to answer exactly this question. In addition we expect to be able, using retardation, aberration and magnetic field line geometry, to determine emission altitudes and vertical extent of layers emitting different intensities and different frequencies.?