The use of the colour-colour plot in the analysis of radio
synchrotron spectra
Peter C. Tribble
Institute of Astronomy, Madingley Road, Cambridge CB3 0HA
Abstract
Katz-Stone et al. have recently introduced the concept of the
colour-colour plot for analyzing radio synchrotron spectra. I present
theoretical colour-colour plots for realistic synchrotron spectra that
allow for the effects of a random magnetic field, inverse Compton
losses, and diffusion of relativistic electrons. I consider the effect
of varying the magnetic field distribution and the set of observing
frequencies. The model colour-colour plots presented here agree with
the data for Cygnus A much better than standard models. The models
indicate that the field strength in Cygnus A exceeds 8.7
, and that electrons are
diffusing slowly between regions of different field strength with a
mean free path to scattering of a few parsecs or less.
Key words: magnetic fields -- radio continuum: galaxies -- radiation
mechanisms: cyclotron and synchrotron
Contents:
- Introduction
- Model colour-colour diagrams
- Sheared field models
- Other field distributions
- Realistic diffusion models
- Two component models
- Application to Cygnus A
- Conclusions
- Acknowledgments
- References
___________________________________
Peter Tribble, peter.tribble@gmail.com