Pulsar emission: Langmuir modes in a relativistic multi-component plasma

Abstract

Ions, protons and possibly a small flux of electrons and positrons are accelerated outward from the polar cap of a normal or millisecond pulsar whose rotational spin is antiparallel with its magnetic moment. The Langmuir modes of this relativistic plasma have several properties of significance for the origin of coherent radio emission. The characteristics of the mode are determined by the sequence of singularities in the dielectric tensor at real angular frequencies, which in turn is fixed by the electron-positron momentum distribution. We find that under a certain condition on its momentum distribution, an electron-positron flux two orders of magnitude smaller than the Goldreich-Julian flux stabilizes the plasma and extinguishes the mode. But more generally, both the growth rate and wavenumber of the multi-component Langmuir mode can be as much as an order of magnitude larger than those of the two-component ion-proton mode. It appears to be a further effective source for the plasma turbulence whose decay is probably responsible for the observed emission.

arXiv comment6 pages, 1 figure

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Cited by in corpus (8)

• Coherent Emission Mechanisms in Astrophysical Plasmas
• Pulsar Electrodynamics: an unsolved problem
• A model of an ion-proton radio pulsar polar cap
• Ion-proton pulsars
• A multi-component Langmuir-mode source for the observed pulsar coherent emission
• Simulations of the radio polarization of a precessing pulsar PSR J1906+0746
• Polar caps in the presence of an induction field
• The Crab pulsar: ion-proton plasma and high-frequency radio spectrum