A model for the challenging "bi-drifting" phenomenon in PSR J0815+09

Abstract

A new drifting pulsar, PSR J0815+09, was discovered in the Arecibo drift-scan searches. An intriguing feature of this source is that within the four pulse components in the integrated pulse profile, the subpulse drifting direction in the two leading components is opposite from that in the two trailing components. In the view that the leading theoretical model for pulsar subpulse drifting can only interpret one-direction subpulse drifting, the observed bi-drifting phenomenon from PSR J0815+09 poses a great challenge to the pulsar theory. The inner annular gap (IAG), a new type of inner particle accelerator, was recently proposed to explain both γ-ray and radio emission from pulsars. Here we show that the coexistence of the IAG and the conventional inner core gap offers a natural interpretation to the bi-drifting phenomenon. In particular, the peculiar drifting behavior in PSR J0815+09 can be reproduced within the inverse Compton scattering model for pulsar radio emission.