Modeling multiband X-ray light curves of the Crab pulsar with the annular and core gap models

Abstract

Multiwavelength observation is an effective way to test and constrain theoretical models of pulsars. X-ray observations reveal that the light curve of the Crab pulsar has two sharp peaks, with a phase separation of ~ 0.4 spin periods between its first peak (P1) and second peak (P2). Using observations from the Hard X-ray Modulation Telescope (Insight-HXMT) of China, we studied eight-wavelength (from 11 keV to 250 keV) X-ray light curves of the Crab pulsar and found that the phase separation has no significant trend with the energy, while the total intensity ratios of the P2 and bridge emission components to the P1 component have a significant increasing trend with increasing energy. We used three-dimensional magnetospheric models for the core gap (CG) and annular gap (AG) to simulate the eight-wavelength X-ray light curves. It was found that the P1, P2 and bridge emission components at each band can be well reproduced by the two models and that the P1 and P2 emissions could be generated in the AG region, whereas the bridge emission could be generated in the CG region.