Mon. Not. R. Astron. Soc., 451, L55-L59 (2015/July-3)
γ-ray emission states in the redback millisecond pulsar binary system PSR J1227-4853.
Abstract (from CDS):
Long expected transition states between the rotation powered and accretion powered non-thermal emission in the millisecond pulsar binary systems have been recently observed in the case of three objects PSR J1023+0038, PSR J1824-2452, and PSR J1227-4859. Surprisingly, the transition is related to the significant change in the γ-ray flux being a factor of a few higher with the presence of an accretion disc. The origin of this enhanced emission seems to be related to the penetration of the inner pulsar magnetosphere by the accretion disc. We propose that the radiation processes, characteristic for the rotation powered pulsar, can co-exist with the presence of an accretion disc in the inner pulsar magnetosphere. In our scenario additional γ-ray emission is produced by secondary leptons, originated close to the acceleration gap, which Compton up-scatter thermal radiation from the accretion disc to GeV energies. The accretion disc penetrates deep into the pulsar magnetosphere allowing the matter to fall on to the neutron star surface producing pulsed X-ray emission. We show that the sum of the rotation powered pulsar γ-ray emission, produced by the primary electrons in the curvature process, and the γ-ray emission, produced by secondary leptons, can explain the observed high-energy radiation from the redback binary pulsar PSR J1227-4853 in the state with evidences of the accretion disc.