Constraints on the Emission Geometry of the ''B'' Pulsar in the Double Pulsar System

We present the evolution of the radio emission from the 2.8 sec pulsar of the double pulsar system J0737-3039A/B. The pulse profiles and the mean flux densities of pulsar B change significantly over five years of observation, culminating in the radio emission disappearance in 2008 March. Over this time, the flux density decreases by 0.177 mJy/yr at the brightest orbital phases and the pulse profile evolves from a single to a double peak, with a separation rate of 2.6 deg/yr. The pulse profile changes are most likely caused by relativistic spin precession and can be explained with an elliptical hollow-cone beam. This particular beam model constrains the geometrical parameters of the pulsar to be consistent with those derived in Breton et al. 2008. The magnetosphere of pulsar B is distorted by the strong stellar wind produced from pulsar A. The influence of these distortions on the orbital-dependent emission properties of pulsar B can be used to determine the location of the coherent radio emission generation region in the pulsar magnetosphere. Using a model of the wind-distorted magnetosphere of pulsar B and the well defined geometrical parameters of the system, we determine the minimum emission height to be 20 neutron star radii in the two bright orbital longitude regions. We can determine the maximum emission height by accounting for the amount of deflection of the polar field line with respect to the magnetic axis. This is estimated to be 2500 neutron star radii. The minimum and maximum emission heights we calculate are consistent with those estimated for normal isolated pulsars.