Scattering and Diffraction in Magnetospheres of Fast Pulsars

Abstract

We show that under conditions of strong density modulation the effects of magnetospheric scintillations in diffractive and refractive regimes may be observable. The most distinctive feature of the magnetospheric scintillations is their independence on frequency. Results based on diffractive scattering due to small scale in homogeneities give a scattering angle that may be as large as 0.1 radians, and a typical decorrelation time of 10⁻⁸ seconds. Refractive scattering due to large scale inhomogeneities is also possible, with a typical angle of 10⁻³ radians and a correlation time of the order of 10⁻⁴ seconds. Temporal variation in the plasma density may also result in a delay time of the order of 10⁻⁴ seconds. The different scaling of the above quantities with frequency may allow one to distinguish the effects of propagation through a pulsar magnetosphere from the interstellar medium. In particular, we expect that the magnetospheric scintillations are relatively more important for nearby pulsars when observed at high frequencies.