Isolated solitons in an ultrarelativistic electron-positron plasma of a pulsar magnetosphere

The nonlinear propagation of intense electromagnetic radiation in an electron-positron plasma of a pulsar magnetosphere is investigated. Basic equations describing a macroscopic behavior of an ultrarelativistic plasma (T≫${\mathrm{mc}}^2$) in a covariant form are used to treat the problem. Relativistic and time-derivative ponderomotive nonlinearities are considered. Earlier results of envelope solitons in the weak relativistic case are confirmed, while isolated solitons are found to exist in the ultrarelativistic plasma.