Induced Compton Scattering in Gigahertz Peak Spectrum Radio Sources

We revisit the shocked shell model for the class of Active Galactic Nuclei known as Gigahertz Peak Spectrum sources, incorporating new observational data on the radiation brightness temperatures. We argue that in addition to free–free absorption, induced Compton scattering will also have an important effect in forming the ∼ GHz peak and in shaping the radio spectra that characterize these sources. Indeed, our arguments suggest that GPS sources may provide the first real evidence for the role of induced Compton scattering in extragalactic radio sources. Subject headings: galaxies: active — shocks — radiation mechanisms: thermal, non–thermal — scattering