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J. Arons (Astronomy Dept., University of California, Berkeley), A. Spitkovsky (Kavli Institute for Particle Astrophysics and Cosmology, Stanford University)
The slow pulsar J0737-3039B in the double pulsar system eclipses the pulsed radio radiation from the fast pulsar J0737-3039A when B crosses the line of sight to A. In addition, over ~90o of orbital phase, the pulsed radiation from B also shows a deep eclipse. Shock heated plasma of the A pulsar's wind enfolding B's magnetosphere in a magnetosheath is the geometrically most efficient model for these phenomena, with incoherent synchrotron absorption in the magnetosheath plasma being the obvious candidate for the mechanism behind the absorption of radio photons. However, when applied to the interpretation of the eclipses, the required density in the wind from A is approximately 5 orders of magnitude larger than is suggested by existing theories of pair creation applied to A's magnetopshere, and 3 orders of magnitude larger than would be expected, using an analogy to the particle injection rates inferred from young pulsar wind nebulae, which are powered by neutron stars with spindown luminosity much larger than that of pulsar A.
We suggest that pitch angle anisotropy and gyrophase coherence in the shocked pair plasma in the magnetosheath enhances the plasma's absorptivity for radio photons, thus reducing the inferred density required to create the observed eclipses. We use particle-in-cell simulations to show that the collisionless shock does create favorable conditions for this form of anomalous absorption to be operative. We show that the requisite gyrophase bunching enhances the synchrotron emission from B's magnetosheath to a level that offers a possible explanation of the unpulsed radio emission observed from this binary system. We also discuss some observational tests of our proposal.
The author(s) of this abstract have provided an email address for comments about the abstract: arons@astron.berkeley.edu
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Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.