Orbital modulation of emission of the binary pulsar J0737-3039B

In the binary radio pulsar system J0737−3039, the slow pulsar B shows intense orbital modulations, with these being especially bright at two short orbital phases. We propose that these modulations are due to distortion of the pulsar B magnetosphere by the pulsar A wind which produces orbital phase-dependent changes in the direction along which the radio waves are emitted. In our model, pulsar B is intrinsically bright at all times but its radiation beam misses the Earth at most orbital phases. We employ a simple model of the distorted B magnetosphere using stretching transformations of Euler potentials of dipolar fields. To fit the observations we use parameters of pulsar B derived from the modelling of A eclipses. The model reproduces two bright regions at approximately the observed orbital phases, explains variations in the pulse shape between them and the regular timing residuals within each emission window. It also makes predictions for the timing properties and secular variations of pulsar B profiles.