Effect of the Kinetic Temperature of Plasma Electrons on Dispersion and Rotation Measures

Abstract

The aim of this work is to analyze the impact of the kinetic temperature of electrons in a warm anisotropic plasma and the strength of its magnetic field on the integral characteristics of pulsar pulsed radio emission propagation, such as the dispersion measure (DM) and rotation measure (RM). An important aspect in this context is the presence of magnetic fields in the plasma, their strength, and their configuration relative to the line of sight. The approach uniquely accounts for polarization splitting into ordinary and extraordinary waves in pulsar pulsed radio emission and considers the limiting cases of quasi-longitudinal and quasi-transverse propagation of these waves in a medium with magnetic fields of various strengths, with or without scattering. This makes it possible to predict a possible dependence of the DM and RM on frequency (not previously anticipated), magnetic field strength, and electron kinetic temperature as well as the amplification of this dependence with increasing magnetic field strength. Notably, the frequency dependence of the DM and RM is more pronounced at low frequencies, with both measures increasing as frequency decreases. Accounting for these dependences when analyzing DM and RM toward different pulsars makes it possible to estimate cosmic magnetoactive plasma parameters, including the range of electron kinetic temperatures and the strengths of longitudinal and transverse magnetic field components along the path of polarized radiation propagation. Thus, using pulsar pulses as probing radio emission makes it possible to study warm magnetoactive plasma with magnetic field strengths of the order of 1–10 G or higher, such as the solar corona, the Jupiter–Io flux tube, and the Earth’s ionosphere.