Evolution of Hard X-Ray Radiation from Clusters of Galaxies: Bremsstrahlung or Inverse Compton Scattering?
We have calculated the evolution of a non-thermal electron population from super-thermal (but weakly relativistic) to highly relativistic energy range in clusters of galaxies. We investigate the evolution of hard X-ray radiation due to both bremsstrahlung and inverse Compton scattering of the cosmic microwave background photons. The bremsstrahlung component is more significant than that of inverse Compton scattering when the momentum spectra of the electron sources are steeper than ~ P-3.0eand vice versa in the case of Coma, where Pe is the electron momentum. The resultant hard X-ray spectra are flatter when the bremsstrahlung component is dominant. When the spectral indices of the source term are in the intermediate range (from -2.5 to -3.5), too much extreme ultraviolet emission is produced. Inverse-Compton-dominant models can reproduce Coma cluster results with reasonable injection rates, which are possible in cluster mergers and/or ambient gas accretion.
Publications of the Astronomical Society of Japan
- Pub Date:
- June 2002
- galaxies: clusters: general;
- galaxies: clusters: individual (Coma);
- intergalactic medium;
- radiation mechanisms : non-thermal;
- 11 pages with 6 figures, Accepted for publication in PASJ