Shevtsova A. Rotation measure of pulsar radio emission at decameter range

The dissertation is devoted to the study of rapid changes in the rotation measure of radio radiation of pulsars closest to the Earth on short time scales in the decameter range. The dissertation proposes an original approach in which the parameters of the propagation medium are dynamically variable in the time scale of one pulse. This approach allows to analize the rapid processes in the upper layers of the magnetosphere of the pulsar and the pulsar wind. It is in these areas that the rotation measure, as a parameter describing the electron concentration and the magnetic field induction parallel to the line of sight, can vary depending on the phase of the individual pulse. The parameters of the radio propagation medium located further from the pulsar are stable at such time scales and cannot change so quickly. The model of polarized pulsed radio pulsar radiation and a model of a weakly anisotropic propagation medium (interstellar, interplanetary and ionospheric plasma), which can be applied to the decameter wavelength range is proposed. Algorithms for estimating dynamically changing parameters of the radio propagation medium are also developed and presented, and the possibility of sounding the upper layers of the pulsar magnetosphere is illustrated. The developed algorithms are used for processing and analysis of polarized radio radiation of registered anomalously intense pulses of pulsars closest to the Earth in the decameter range. Observations were held on a UTR-2 radio telescope in the range of 16 33 MHz. Only this radio telescope with an effective area of 150,000 m2 at 25 MHz allow to record anomalously intense pulses of pulsars with high time and frequency resolution in this range. For the radio emission of the three pulsars closest to the Earth, estimates of the average absolute values of the rotation measure in the decameter range were obtained. Moreover, for the pulsar J0242 + 6256 estimates of rotation measure were obtained for the first time in the world. Estimates of the degree of rotation for J0814 + 7429 (B0809 + 74), J0953 + 0755 (B0950 + 08) are close to those obtained at higher frequencies. Estimation of rapid changes in the rotation measure of radio pulsars on short time scales using a new method allows to analyze rapid processes in plasma along the line of sight, which creates the preconditions for probing the upper magnetosphere of the pulsar and pulsar wind.