Open AccessOn the electric field screening by electron–positron pairs in a pulsar magnetosphere
Author(s) -
Shibata S.,
Miyazaki J.,
Takahara F.
Publication year - 1998
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1998.01448.x
Subject(s) - physics , pulsar , electric field , magnetosphere , electron , space charge , positron , field (mathematics) , atomic physics , flux (metallurgy) , excited state , particle acceleration , electric current , astrophysics , computational physics , magnetic field , nuclear physics , quantum mechanics , mathematics , pure mathematics , materials science , metallurgy
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 M c =10 3 –10 5 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.