ON THE TRANSITION FROM ACCRETION-POWERED TO ROTATION-POWERED MILLISECOND PULSARS

The heating associated with the deposition of γ-rays in an accretion disk is proposed as a mechanism to facilitate the transformation of a low-mass X-ray binary to the radio millisecond pulsar (MSP) phase. The γ-ray emission produced in the outer gap accelerator in the pulsar magnetosphere likely irradiates the surrounding disk, resulting in its heating and the possible escape of matter from the system. We apply the model to PSR J1023+0038, which has recently been discovered as a newly born rotation-powered MSP. The predicted γ-ray luminosity ∼6 × 1034 erg s-1 can be sufficient to explain the disappearance of the truncated disk existing during the 8 month–2 yr period prior to the 2002 observations of J1023+0038 and the energy input required for the anomalously bright optical emission of its companion star.