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Title: ELECTRODYNAMICS OF AXISYMMETRIC PULSAR MAGNETOSPHERE WITH ELECTRON-POSITRON DISCHARGE: A NUMERICAL EXPERIMENT

Abstract

We present the first self-consistent global simulations of pulsar magnetospheres with operating e {sup ±} discharge. We focus on the simple configuration of an aligned or anti-aligned rotator. The star is spun up from a zero (vacuum) state to a high angular velocity, and we follow the coupled evolution of its external electromagnetic field and plasma particles using the ''particle-in-cell'' method. A plasma magnetosphere begins to form through the extraction of particles from the star; these particles are accelerated by the rotation-induced electric field, producing curvature radiation and igniting e {sup ±} discharge. We follow the system evolution for several revolution periods, longer than required to reach a quasi-steady state. Our numerical experiment puts to test previous ideas for the plasma flow and gaps in the pulsar magnetosphere. We first consider rotators capable of producing pairs out to the light cylinder through photon-photon collisions. We find that their magnetospheres are similar to the previously obtained force-free solutions with a Y-shaped current sheet. The magnetosphere continually ejects e {sup ±} pairs and ions. Pair creation is sustained by a strong electric field along the current sheet. We observe powerful curvature and synchrotron emission from the current sheet, consistent with Fermi observationsmore » of gamma-ray pulsars. We then study pulsars that can only create pairs in the strong-field region near the neutron star, well inside the light cylinder. We find that both aligned and anti-aligned rotators relax to the ''dead'' state with suppressed pair creation and electric currents, regardless of the discharge voltage.« less

Authors:
Publication Date:
OSTI Identifier:
22364916
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 795; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANGULAR VELOCITY; AXIAL SYMMETRY; COMPUTERIZED SIMULATION; ELECTRIC CURRENTS; ELECTRIC FIELDS; ELECTRODYNAMICS; ELECTROMAGNETIC FIELDS; ELECTRONS; GAMMA RADIATION; MAGNETIC FIELDS; NEUTRON STARS; NEUTRONS; PAIR PRODUCTION; PLASMA; POSITRONS; PULSARS; STEADY-STATE CONDITIONS; VISIBLE RADIATION

Citation Formats

Chen, Alexander Y., and Beloborodov, Andrei M., E-mail: amb@phys.columbia.edu. ELECTRODYNAMICS OF AXISYMMETRIC PULSAR MAGNETOSPHERE WITH ELECTRON-POSITRON DISCHARGE: A NUMERICAL EXPERIMENT. United States: N. p., 2014. Web. doi:10.1088/2041-8205/795/1/L22.
Chen, Alexander Y., & Beloborodov, Andrei M., E-mail: amb@phys.columbia.edu. ELECTRODYNAMICS OF AXISYMMETRIC PULSAR MAGNETOSPHERE WITH ELECTRON-POSITRON DISCHARGE: A NUMERICAL EXPERIMENT. United States. https://doi.org/10.1088/2041-8205/795/1/L22
Chen, Alexander Y., and Beloborodov, Andrei M., E-mail: amb@phys.columbia.edu. 2014. "ELECTRODYNAMICS OF AXISYMMETRIC PULSAR MAGNETOSPHERE WITH ELECTRON-POSITRON DISCHARGE: A NUMERICAL EXPERIMENT". United States. https://doi.org/10.1088/2041-8205/795/1/L22.
@article{osti_22364916,
title = {ELECTRODYNAMICS OF AXISYMMETRIC PULSAR MAGNETOSPHERE WITH ELECTRON-POSITRON DISCHARGE: A NUMERICAL EXPERIMENT},
author = {Chen, Alexander Y. and Beloborodov, Andrei M., E-mail: amb@phys.columbia.edu},
abstractNote = {We present the first self-consistent global simulations of pulsar magnetospheres with operating e {sup ±} discharge. We focus on the simple configuration of an aligned or anti-aligned rotator. The star is spun up from a zero (vacuum) state to a high angular velocity, and we follow the coupled evolution of its external electromagnetic field and plasma particles using the ''particle-in-cell'' method. A plasma magnetosphere begins to form through the extraction of particles from the star; these particles are accelerated by the rotation-induced electric field, producing curvature radiation and igniting e {sup ±} discharge. We follow the system evolution for several revolution periods, longer than required to reach a quasi-steady state. Our numerical experiment puts to test previous ideas for the plasma flow and gaps in the pulsar magnetosphere. We first consider rotators capable of producing pairs out to the light cylinder through photon-photon collisions. We find that their magnetospheres are similar to the previously obtained force-free solutions with a Y-shaped current sheet. The magnetosphere continually ejects e {sup ±} pairs and ions. Pair creation is sustained by a strong electric field along the current sheet. We observe powerful curvature and synchrotron emission from the current sheet, consistent with Fermi observations of gamma-ray pulsars. We then study pulsars that can only create pairs in the strong-field region near the neutron star, well inside the light cylinder. We find that both aligned and anti-aligned rotators relax to the ''dead'' state with suppressed pair creation and electric currents, regardless of the discharge voltage.},
doi = {10.1088/2041-8205/795/1/L22},
url = {https://www.osti.gov/biblio/22364916}, journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 1,
volume = 795,
place = {United States},
year = {Sat Nov 01 00:00:00 EDT 2014},
month = {Sat Nov 01 00:00:00 EDT 2014}
}