GRO J1744-28: The luminosity and pulsar emission mechanism

The recent detection of the super-Eddington persistent luminosity of the bu rsting pulsar GRO J1744-28 suggests that the X-ray radiation in this object is emitted by the side walls of high accretion columns standing on the mag netic polar caps. We show that the observed energy dependence of the pulsed fraction in the X-ray Bur of GRO J1744-28 can result from a non-uniform di stribution of the effective emission temperature over the height of the col umn. The effect of gravitational light bending near the surface of the neut ron star must be taken into account.