The radiation of ultrarelativistic particles is examined in a quasi-uniform magnetic field superimposed by a wide spectrum of magnetic, electric, and electron density inhomogeneities created in a turbulent plasma. The radiation spectrum from a particle of a given energy is shown to acquire a high-frequency power-law tail with the same spectral index as the index ν of small-scale turbulence. For a power-law spectrum of ultrarelativistic electrons, d N(ℰ)/dℰ ~ ℰ-ξ, with a cut-off at some energy ℰmax, the radiation spectrum consists of a few power-law ranges; the radiation intensity may suffer jumps at frequencies which separate these ranges. In the high-frequency range the spectral index ν is determined by small-scale magnetic and electric fields. At intermediate frequencies the main contribution comes from the synchrotron radiation in a large-scale field; the radiation spectrum has an index α=(ζ-1)/2. The same index may be produced by large-scale Langmuir waves. At lower frequencies the radiation spectrum increases owing to the transition radiation caused by electron density fluctuations; in this case the spectral index is equal to ζ+1-ν. The possibility of diagnostics of high-frequency cosmic plasma turbulence from radiation of high-energy particles is discussed. It is shown that the proposed theory may explain some features in the spectra of several cosmic objects.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science