Effects of Gyroresonance Absorption and Self Absorption on the Gyrosynchrotron Radiation Spectrum

Effects of gyroresonance absorption and self absorption on the gyrosynchrotron radiation spectrum are investigated with a model in a magnetic dipole field. It is found that the gyroresonance absorption and self absorption suppress substantially the gyrosynchrotron radiation at lower frequencies where the radio source is optically thick. The suppression of the gyroresonance absorption on the spectrum increases with the increasing temperature and density of thermal electrons. The suppression of the self absorption on the spectrum increases as increasing number density of the nonthermal electrons. The influences of the gyroresonance absorption and the self one on the spectrum are compared quantitatively. It is shown that only when the number density of the nonthermal electron reaches a higher value of about 3×10⁴cm^-3 above 10keV, can the effect of the self absorption on the spectrum compare with the effect of the gyroresonance absorption.