Anisotropic Emission and the Radio-Loud/Radio-Quiet Problem of Active Galactic Nuclei, Quasi-Stellar Objects

The possibility that radio-quiet active galactic nuclei (AGN) are those that have misdirected anisotropic radio-x-ray emission is considered and ruled out. Rather it is argued that they are systems with fundamentally different physics. Arguments are also presented that the so-called radio-quiet quasi-stellar objects (QSOs) are not self-absorbed nonthermal sources. Both radio-quiet AGN and QSOs are probably compact thermal (CT) systems in which, lacking any better alternative hypothesis, thermal accretion is the predominant luminosity production mechanism. The terms radio loud and radio quiet should be reconsidered (or at least defined consistently) because some objects have sufficient radio emission to be classified by some definitions as radio loud, yet they are best described as CT from an analysis of their spectral distribution, with essentially no significant luminosity produced by nonthermal processes. Estimates of the intrinsic far-mid-infrared spectral slope of CT sources and the efficiency of relativistic particle acceleration in these objects are also made. CT sources are expected to have relatively flat [F(nu)proportional to upsilon(-1),nu F nu proportional to nu degrees] infrared spectra in general agreement with observation. (C) 1996 American Astronomical Society.