The spectral properties of BL Lac objects

Abstract

A model of plasma reactor is examined for a unified interpretation of the radiation of active galactic nuclei and, particularly, of BL Lac objects. The physical scenario is as follows: a large number of relativistic electrons are ejected by the central engine into the plasma reactor which surrounds the central core, and rapidly lose their energy by synchrotron radiation. Meanwhile, these electrons are accelerated by absorbing synchrotron radiation which is not transparent in the plasma reactor and set up a steady and isotropic power law distribution with spectral index γ=3. Then they emerge through surface diffusion or outburst of the plasma reactor and generate low-frequency synchrotron radiation. The higher frequency synchrotron radiation produced by the plasma reactor shows a rapid spectral steepening as the flux decreases. The properties of synchrotron radiation source with radiation loss and injection of relativistic electrons are studied in detail.