synchrotron self-Compton

Synchrotron self-Compton (SSC or synchro-Compton) is scattering of synchrotron radiation by the same cloud of particles producing the radiation. The scattering is inverse Compton scattering in which the particle transfers energy to the photon, increasing the photon's frequency and energy and decreasing its wavelength. The process leaves a signature in the spectral energy distribution (SED), offering hints to the nature of the cloud.

The synchro-Compton catastrophe is a phenomenon occurring in the presence of so many relativistic electrons that radio photons produced through synchrotron are all converted through SSC to gamma rays or X-rays, i.e., no radio is left.