The double pulsar system J0737-3039: Modulation of the radio emission from B by radiation from A

We have analyzed single pulses from PSR J0737-3039B, the 2.8 s pulsar in the recently discovered double pulsar system, using data taken with the Green Bank Telescope at 820 and 1400 MHz. We report the detection of features similar to drifting subpulses, detectable over only a fraction of the pulse window, with a fluctuation frequency of 0.196 cycles per period. This is exactly the beat frequency between the periods of the two pulsars. In addition, the drifting features have a separation within a given pulse of 23 ms, equal to the pulse period of A. These features are therefore due to the direct influence of J0737-3039A's 44 Hz electromagnetic radiation on J0737-3039B's magnetosphere. We only detect them over a small range of orbital phases, when the radiation from the recycled pulsar J0737-3039A meets our line of sight to J0737-3039B from the side.