The influence of the ionized medium on synchrotron emission spectra in the solar corona

Suppression of synchrotron emission at low frequencies owing to the influence of the ionized coronal plasma is proposed to account for the observed low frequency cutoff in type IV radio bursts Since in a plasma the index of refraction is frequency dependent and less than unity, the phase velocity of electromagnetic waves is greater than c at low frequencies with the result that synchrotron emission is suppressed. A calculation is made of the synchrotron emission resulting from high-energy electrons radiating in the coronal plasma, and these spectra exhibit sharp low-frequency cutoffs similar to those observed in type IV meter and decimeter radio bursts.

[1]  V. Trakhtengerts,et al.  Influence of the Medium on Generation of Type-IV Solar Radio Emission , 1966 .

[2]  H. J. Hagger,et al.  Solar Radio Astronomy , 1965 .

[3]  G. Fazio,et al.  The gamma‐ray spectrum of the Sun , 1965 .

[4]  A. Fokker.  Type IV solar radio emission , 1963 .

[5]  W. Webber,et al.  Exponential rigidity spectrums for solar‐flare cosmic rays , 1963 .

[6]  G. Newkirk.  The Solar Corona in Active Regions and the Thermal Origin of the Slowly Varying Component of Solar Radio Radiation. , 1961 .

[7]  T. Takakura.  Synchrotron radiation from intermediate energy electrons and solar radio outbursts at microwave frequencies. , 1960 .

[8]  K. C. Westfold,et al.  The Polarization of Synchrotron Radiation. , 1959 .

[9]  R. McCray.  The Electromagnetic Spectrum of Eta Carinae , 1967 .

[10]  T. Takakura.  Implications of solar radio bursts for the study of the solar corona , 1966 .

[11]  V. L. Ginzburg,et al.  Cosmic Magnetobremsstrahlung (Synchrotron Radiation) , 1965 .

[12]  P. Scheuer.  Radio Structure of 3c 273 and Spectra of Radio Sources , 1965 .

[13]  H. Friedman.  ULTRAVIOLET AND X RAYS FROM THE SUN , 1963 .

[14]  E. Ney,et al.  Continuum electromagnetic radiation from solar flares , 1963 .

[15]  A. Weiss.  The Positions and Movements of the Sources of Solar Radio Bursts of Spectral Type II , 1963 .

[16]  K. Kai,et al.  HEIGHT AND MOTION OF THE SOLAR RADIO BURSTS AT 200 Mc/s , 1962 .

[17]  A. R. Thompson,et al.  Spectral Observations of Solar Radio Bursts. II. Slow-Drift Bursts and Coronal Streamers. , 1962 .

[18]  K. Kai,et al.  Spectra of Solar Radio Type IV Bursts , 1961 .

[19]  A. Boischot.  Caractères d'un type d'émission hertzienne associé à certaines éruptions chromosphériques , 1957 .