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Theory of pulsars - Polar caps, sparks, and coherent microwave radiation

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1975

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A polar magnetospheric gap forms above a neutron star’s surface, extending ~10 km, with a ~10^12 V potential that repeatedly discharges via electron‑positron pair production on microsecond timescales, driving the pulsar’s homopolar generator. The model accounts for many observed properties of pulsars’ coherent microwave emission. Published in The Astrophysical Journal (Feb 1975), DOI 10.1086/153393.

Abstract

view Abstract Citations (2040) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Theory of pulsars: polar gaps, sparks, and coherent microwave radiation. Ruderman, M. A. ; Sutherland, P. G. Abstract Several consequences are derived for a neutron star whose magnetic moment tends to be antiparallel to its spin angular momentum, when emitted electrons do not return to the star through the light cylinder along the open field lines. A polar magnetospheric gap is formed that spans the open field lines from the stellar surface up to an altitude of about 10,000 cm. The scalar product of the electric and magnetic fields is nonzero in the gap, although it vanishes essentially everywhere else in the near magnetosphere. The potential difference between the base and the top of the gap is about 1 trillion volts. The gap continually breaks down by forming electron-positron pairs on a time scale of a few microseconds. The gap positrons move out along the open field lines and electrons flow to the stellar surface to close the pulsar's homopolar generator circuit. The proposed model can explain many characteristics of the coherent microwave radiation observed from pulsars. Publication: The Astrophysical Journal Pub Date: February 1975 DOI: 10.1086/153393 Bibcode: 1975ApJ...196...51R Keywords: Coherent Electromagnetic Radiation; Neutron Stars; Pulsars; Stellar Atmospheres; Stellar Magnetic Fields; Angular Momentum; Astronomical Catalogs; Electron-Positron Pairs; Lines Of Force; Magnetospheres; Microwaves; Positrons; Relativistic Particles; Stellar Envelopes; Stellar Evolution; Astrophysics full text sources ADS | data products SIMBAD (5)