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Title: A fan beam model for radio pulsars. I. Observational evidence

We propose a novel beam model for radio pulsars based on the scenario that the broadband and coherent emission from secondary relativistic particles, as they move along a flux tube in a dipolar magnetic field, form a radially extended sub-beam with unique properties. The whole radio beam may consist of several sub-beams, forming a fan-shaped pattern. When only one or a few flux tubes are active, the fan beam becomes very patchy. This model differs essentially from the conal beam models with respect to the beam structure and predictions on the relationship between pulse width and impact angle β (the angle between the line of sight and the magnetic pole) and the relationship between emission intensity and beam angular radius. The evidence for this model comes from the observed patchy beams of precessional binary pulsars and three statistical relationships found for a sample of 64 pulsars, of which β were mostly constrained by fitting polarization position angle data with the rotation vector model. With appropriate assumptions, the fan beam model can reproduce the relationship between 10% peak pulse width and |β|, the anticorrelation between the emission intensity and |β|, and the upper boundary line in the scatter plot of |β|more » versus pulsar distance. An extremely patchy beam model with the assumption of narrowband emission from one or a few flux tubes is studied and found unlikely to be a general model. The implications of the fan beam model for the studies on radio and gamma-ray pulsar populations and radio polarization are discussed.« less
Authors:
; ; ; ; ; ; ;  [1] ;  [2]
  1. School of Physics and Electronic Engineering, Guangzhou University, 510006 Guangzhou (China)
  2. College of Physical Science and Technology, Huazhong Normal University, 430079 Wuhan (China)
Publication Date:
OSTI Identifier:
22356451
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 789; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BEAMS; EMISSION; GAMMA RADIATION; MAGNETIC FIELDS; POLARIZATION; PULSARS; RELATIVISTIC RANGE; ROTATION