Radio synchrotron emission by protons and electrons in pulsars and the nuclei of quasars

Relations enabling estimation of the limiting brightness temperature of syn chrotron radiation subject to self-absorption and inverse Compton scatterin g are presented for the case of relativistic electrons (positrons) and prot ons. Analogous expressions are presented for relativistic particles moving along curved magnetic lines of force (curvature radiation) and coherent rad iation by relativistic particles. These relations can be used to determine the brightness temperatures expected for the central regions of active gala ctic nuclei, neutron stars, and other objects that produce relativistic par ticles. Radiation by relativistic protons yields higher intensities, and co uld be a source of the highest-energy cosmic rays. (C) 2000 MAIK "Nauka/lnt erperiodica".