Radio-far-infrared Correlation and Cosmic Ray Electrons in Starburst Galaxies and Ultra Luminous Infrared Galaxies

The ubiquitous and tight correlation between the radio continuum emission and the far-infrared emission is also found to hold true for starburst galaxies and Ultra Luminous Infrared Galaxies wherein most of the emission is from compact structures. The infrared photon density in the cores is high enough for the inverse Compton scattering to dominate over the synchrotron emission thus spoiling the correlation. The high magnetic field postulated to avoid this, also encounters the problem of steep radio index that is not observed. Further, at high densities the flux of secondary electrons can exceed that of the primary. The problems posed by such effects are discussed and suggestion for further work made.