Journal Article

On the electric field screening by electron-positron pairs in a pulsar magnetosphere

S. Shibata, J. Miyazaki and F. Takahara

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 295, issue 4, pages L53-L58
Published in print April 1998 | ISSN: 0035-8711
Published online April 1998 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1046/j.1365-8711.1998.01448.x
On the electric field screening by electron-positron pairs in a pulsar magnetosphere

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Abstract

We present a steady one-dimensional model for a pulsar polar cap accelerator, where the field-aligned electric field and flow are solved self-consistently with a given current density. It is assumed that no particles return to the star. It is known that the space-charge-limited flow is accelerated to energies high enough to create electron-positron pairs if the assumed current density is high enough. We find that when pairs are created in such a space-charge-limited flow, the accelerating electric field is screened out within a short distance after pair creation, if the pair particle flux is larger than a critical value. We also find that a space charge density wave is excited in the screening region.

We find that a pair flux larger than the critical value Mc=103−105 must be reached in a layer with thickness equal to the braking distance for the decelerating component. Therefore, the required multiplicity — the number of pairs created by one primary particle — is too large to be realized in the actual pulsar magnetosphere. We suggest that in order to obtain a localized potential drop along the polar cap magnetic flux, one needs to take into account additional effects such as wave-particle interaction or quasi-periodic pair creation.

Keywords: magnetic fields; plasmas; pulsars: general; gamma-rays: theory

Journal Article.  0 words. 

Subjects: Astronomy and Astrophysics

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