Energy dependence of x-ray pulse profile of the crab pulsar

Abstract

We obtained pulse profiles of Crab pulsar in 4 different X-ray energy bands between 2 and 30 keV. We found that all the profiles in these energy ranges show two peaks occurring at the same phase joined by a lower but non zero flux region named as the bridge. Intergrated flux or fluence of peak-2 and bridge show energy dependent variation with respect to peak-I. These fluence ratios increase with energy in a similar pattern indicating common origin for these changes. These increasing trends of the fluence ratios have different implications on current pulsar emission models and offer new challenges for refinement of existing models.