The Geminga fraction |
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| Authors: | Alice K Harding Isabelle A Grenier Peter L Gonthier |
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| Institution: | (1) Code 663, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA;(2) AIM, Service d’Astrophysique, CEA Saclay, 91191 Gif Sur Yvette, France;(3) Dept. of Physics, Hope College, 27 Graves Place, Holland, MI 49423, USA |
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| Abstract: | Radio-quiet γ-ray pulsars like Geminga may account for a number of the unidentified EGRET sources in the Galaxy. The number of Geminga-like
pulsars is very sensitive to the geometry of both the γ-ray and radio beams. Recent studies of the shape and polarization of pulse profiles of young radio pulsars have provided
evidence that their radio emission originates in wide cone beams at altitudes that are a significant fraction (1–10%) of their
light cylinder radius. Such wide radio emission beams will be visible at a much larger range of observer angles than the narrow
core components thought to originate at lower altitude. Using 3D geometrical modeling that includes relativistic effects from
pulsar rotation, we study the visibility of such radio cone beams as well as that of the γ-ray beams predicted by slot gap and outer gap models. From the results of this study, one can obtain revised predictions
for the fraction of Geminga-like, radio quiet pulsars present in the γ-ray pulsar population.
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| Keywords: | Pulsars γ -Ray sources Pulsar populations Non-thermal radiation |
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