The radiative processes in dense magnetized plasma: application to pulsars

It is well known that plasma processes play a decisive role in the generation of emission from many astrophysical objects. An excellent example of a space laboratory for plasma physics is a magnetized neutron star and its environment. If the frequency of radiation is less than that of the plasma and/or cyclotron frequencies, the radiation mechanism should be coherent. Therefore, high energy (i.e. x- and gamma-ray) emission can usually be explained by a single-particle radiation (excluding the black-body radiation from very hot spots), but the radio and optical radiation must be generated due to some plasma instabilities. This paper brings an overview of linear and nonlinear processes in such plasmas and addresses possibilities of their application for astrophysical purposes. It should be mentioned that generation of waves is a necessary but insufficient condition for radiation mechanisms. Though the plasma waves often possess the highest growth rate, they cannot escape from the plasma. Quite often it is not enough to generate turbulence in the source, but it is also necessary to find a mechanism that ensures transformation of plasma waves into waves capable of escaping from the source and reaching the observer.