Pulsar radio emission

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A new version of the theory of pulsar radio emission is developed for the case of a coaxial rotator. It is based on the electric field that we established [G. S. Sahakian, Astrofizika, 37, 97 (1994)] for the radiation channel (the channel of open magnetic field lines) and on convenient approximations for the electron energy obtained in [G. S. Sahakian and E. S. Chubarian, Astrofizika, 37, 255 (1994)]. It is shown that, owing to the emission of photons of curvature radiation by particles, e → e+ħωc', and photon annihilation, ħωc → e+e− in the lower part of the radiation channel, a special region (the magnetic funnel) is formed in which vigorous cascade multiplication of particles occurs. The height of the magnetic funnel is h ≈ 6RΩ0.2, where R is the radius of the neutron star and Ω is its angular rotation rate. As a result of supersaturation of the plasma density in the magnetic funnel, a discharge occurs after each time intervalt≈5·10−7Ω−0.8B 12 −1.4 R 6 −0.2 , i.e., the longitudinal electric field disappears (B is the magnetic induction in the star). During the active radiative processes in the magnetic funnel, two main fluxes of particles with high ultrarelativistic energies are formed: an upward flux of electrons and a positron flux falling onto the star's magnetic cap. These fluxes are accompanied by narrow strips of positron and electron fluxes, respectively, of considerably lower energy, which are fairly powerful, coherent radio sources. The pulsar's radio luminosity is calculated to be L≈7.4·1022Ω3.8μ 30 3 R 6 −2 erg/sec, where μ=BR 3/2 is the star's magnetic moment. Comparing this result with observations, we conclude that the magnetic moment and hence the mass of the neutron star evidently must be considerably smaller, on the average, for fast pulsars than for slow ones. It is shown that the magnetic moment of the neutron star can be determined from the intervals between micropulses in the pulse profiles. The problem of the origin of the macrostructure of the radio pulse is discussed.