The Physical Effects of Relativistic Electrons and their Applications for High-energy Objects

In the present paper, the emissive properties, energy spectral evolutions and acceleration mechanisms of relativistic electrons are introduced. The roles of relativistic electrons on the radiation properties of high-energy objects are briefly discussed. Based on the physical effects of relativistic electrons, it is studied for the emissive mechanisms of the radio radation and spectral variability of blazars, the emissive mechanism of BL Lac objects and gamma-ray bursts. The main results are: 1. An optically thin synchrotron emission model based on evolutionary relativistic electron spectra is developed to explain radio flat spectra of blazars. The basic physical processes of relativistic electron spectrum evolution for synchrotron emission are second-order Fermi acceleration of turbulent plasmawaves, Fermi acceleration of shock waves, radiation losses, particle escape, and adiabatic deceleration in a flow of synchrotron plasma. These processes cause the relativistic electron spectrum to be flat and to produce the synchrotron radiation with flat spectrum in radio frequencies.2. The evolution of the relativistic electron spectrum in a homogeneous jet due to the injection of fresh relativistic electrons, radiation losses, and particle escape is considered and applied to the interpretation of the spectral variability of blazars at high frequencies. These processes cause the fast variability of relativistic electron spectra and produce the spectral variability of blazar radiations at high frequencies.3. A plasma reactor model is examined for a unified interpretation of the radiation of BL Lac objects. The basic 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 their energy rapidly lose by synchrotron radiation. Meanwhile, these electrons are accelerated by absorbing synchrotron radiation which is not transparents in the plasma reactor and set up a steady and isotropic power law distribution with spectral index γ=3. 0. Then they emerge through surface diffusion or outburst of the plasma reactor and generate low-frequency synchrotron radiation. The model is applied to explain the spectral properties of BL Lac objects, that is, a rapid spectral steeping as the flux decreases.4. An internal shock wave model is examined to explain the spectra and time structures of the pulse in gamma-ray bursts. The basic physical scenario is: two internal shock waves are formed in the relativistic shell caused by outbust of the original objects. The shocks propogate in the relativistic shell and exhaust its motion energy, and accelerate some electrons to be relativistic electrons, then these electrons produce the observed gamma-ray radiation through synchrotron emission. The model suggests that the simple gamma-ray bursts are associated with single shock emission episodes, and the complex gamma-ray bursts might result from the superposition of the components which originate from the shocks forming at different shell region.