Probing Relativistic Winds: The case of PSRJ07370-3039 A & B

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 PSRJ07370-3039 A & B. The model predicts the eclipses will clear at frequencies higher than those of the observations reported to date (nominally, above $\nu \sim 5$ GHz.) The model also predicts synchrotron emission at the level of a few to 10 $\mu$Jy, peaking at $\nu \sim 2-5$ GHz with possible orbital modulation. We use simplified semi-analytic models and particle-in-cell simulations to elucidate the structure of the B magnetosphere, showing that B's magnetic field is confined to within a radius less than 50,000 km from B,on the side facing A. We estimate a ``propellor'' spindown torque on B, which is the dominant torque on this star, which yields a polar dipole field $\sim 7 \times 10^{11}$ Gauss (magnetic moment $\mu_B \sim 3.5 \times 10^{29}$ cgs). 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 popular pair creation models, and discuss the implications of this result for our general understanding of pulsar physics. Our proposal was outlined in Kaspi et al. (2004) and Demorest et al. (2004); a similar proposal has been made by Lyutikov (2004).