On the content of cold electrons and positrons in relativistic jets

We analyze the possibility to determine the plasma composition of relativistic jets in blazars and microquasars from the data on polarization and intensity of their synchrotron radiation in the radio frequency band. We propose a universal plot that allows to determine the abundance of nonrelativistic electrons and the presence of positrons in the specific objects from their intensity frequency spectra and polarization at several frequencies. As a result, we find that electron plasma component in the jets of the blazars 3C 279 and BL Lacertae is relativistic. In the jets of the microquasar GRS 1915+105, the cold plasma density can be comparable or significantly exceeds the relativistic particle density. The observed parameters of the jet of 3C 279 does not require the necessary presence of positrons in it. The details of the proposed approach are presented in the paper [12]. 1