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| Paper: |
Probing Relativistic Winds: The Case of PSR J0737-3039 A and B |
| Volume: |
328, Binary Radio Pulsars |
| Page: |
95 |
| Authors: |
Arons, J.; Backer, D.C.; Spitkovsky, A.; Kaspi, V.M. |
| Abstract: |
We propose synchrotron absorption in a magnetosheath forming a cocoon around the magnetosphere of pulsar B to be the origin of the eclipse phenomena seen in the recently discovered double pulsar system PSR J0737−3039 A & B. The magnetosheath enfolds the magnetosphere of pulsar B, where the relativistic wind from A collides with B's magnetic field. If this model is correct, it predicts the eclipses will clear at frequencies higher than those of the observations reported to date (nominally, above ν ~ 5 GHz). The model also predicts synchrotron emission at the level of a few to 10 μJy, peaking at ν ~ 2 − 5 GHz with possible orbital modulation. We use simplified semi-analytic models to elucidate the structure of the B magnetosphere, showing that the A wind's dynamic pressure confines B's magnetic field to within a radius less than 50,000 km from B, smaller than B's light cylinder radius, on the "daytime" side (the side facing A). Downstream of B ("nighttime"), B forms a magnetotail. We use particle-in-cell simulations to include the effects of magnetospheric rotation, showing that the magnetosheath has an asymmetric density distribution which may be responsible for the observed eclipse asymmetries. We use simple estimates based upon the magnetic reconnection observed in the simulations to derive a "propellor" spindown torque on B, which is the dominant mode of angular momentum extraction from this star. Application of this torque to B's observed spindown yields a polar dipole field ~ 7 × 1011 Gauss (magnetic moment μB ~ 3.5 × 1029 cgs). This torque has a braking index of unity. We show that the model can explain the known eclipses only if the A wind's density is at least 4 orders of magnitude greater than is expected from existing popular models of pair creation in pulsars. We discuss the implications of this result for our general understanding of pulsar physics.
Our proposal was qualitatively outlined in Kaspi et al. (2004) and Demorest et al. (2004). Since those papers' appearance, a similar proposal has been made by Lyutikov (2004). |
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