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Title: DEAD ZONE IN THE POLAR-CAP ACCELERATOR OF PULSARS

We study plasma flows above pulsar polar caps using time-dependent simulations of plasma particles in the self-consistent electric field. The flow behavior is controlled by the dimensionless parameter {alpha} = j/c{rho}{sub GJ}, where j is the electric current density and {rho}{sub GJ} is the Goldreich-Julian charge density. The region of the polar cap where 0 < {alpha} < 1 is a {sup d}ead zone{sup -}in this zone, particle acceleration is inefficient and pair creation is not expected even for young, rapidly rotating pulsars. Pulsars with polar caps near the rotation axis are predicted to have a hollow-cone structure of radio emission, as the dead zone occupies the central part of the polar cap. Our results apply to charge-separated flows of electrons (j < 0) or ions (j > 0). In the latter case, we consider the possibility of a mixed flow consisting of different ion species, and observe the development of two-stream instability. The dead zone at the polar cap is essential for the development of an outer gap near the null surface {rho}{sub GJ} = 0.
Authors:
;  [1]
  1. Physics Department and Columbia Astrophysics Laboratory, Columbia University, 538 West 120th Street, New York, NY 10027 (United States)
Publication Date:
OSTI Identifier:
22167287
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 762; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ASTRONOMY; ASTROPHYSICS; CHARGE DENSITY; COMPUTERIZED SIMULATION; COSMIC ELECTRONS; ELECTRIC CURRENTS; ELECTRIC FIELDS; IONS; MAGNETIC FIELDS; NEUTRON STARS; PAIR PRODUCTION; PHOTON EMISSION; PLASMA; PULSARS; ROTATION; TIME DEPENDENCE; TWO-STREAM INSTABILITY; ZONES