Pulsar radio emission from beam plasma instability
Abstract
A two step maser mechanism has been recently proposed for the pulsar radio emissions: a spatial modulation of the density of relativistic particles results from an electrostatic beam plasma instability; the bunches of particles flowing along curved magnetic field lines coherently radiate electromagnetic radio waves. In this work, it is shown that such a mechanism is not correct. For this purpose, the relativistic beam plasma instability is reconsidered including in the analysis the curvature of magnetic field lines and finite transverse beam dimensions (the very large magnetic field value expected for neutron stars allows a great simplification in the algebra). The electrostatic and electromagnetic waves, respectively and separately involved in the previous treatments of instability and radiation, are in fact one and the same wave. Nevertheless, the fully electromagnetic Alfven wave instability is not efficient with pulsar parameters. The main result of the work is that the finite beam dimensions provide a natural coupling between the most unstable quasi-electrostatic beam plasma wave and a fully electromagnetic vacuum wave.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1980
- DOI:
- 10.1086/158153
- Bibcode:
- 1980ApJ...239..661A
- Keywords:
-
- Magnetohydrodynamic Stability;
- Pulsars;
- Radio Emission;
- Stellar Radiation;
- Electron Plasma;
- Electrostatic Waves;
- Neutron Stars;
- Plasma-Particle Interactions;
- Radio Sources (Astronomy);
- Relativistic Electron Beams;
- Astrophysics