10-year Fermi LAT results for the Crab pulsar

We fitted power-law models to the overlapping energy spectra from 10GeV to ~1TeV. In the fit, we included a relative cross-calibration of energy scales between air-shower-based gamma-ray telescopes with the orbital pair-production telescope from the Fermi mission. We confirm the energy-dependence of the gamma-ray pulse shape and, equivalently, the phase-dependence of the spectral shape for the Crab pulsar.

A relatively sharp cutoff at a relatively high energy of ~8GeV is observed for the bridge-phase emission. The E>10 GeV spectrum observed for the second pulse peak is harder than those for other phases. In view of the diversity of phase-resolved spectral shapes of the Crab pulsar, we tentatively propose a multi-origin scenario where the polar-cap, outer-gap, and relativistic-wind regions are involved.