So far, the six brightest gamma-ray pulsars, which allow us to measure
their detailed phase-resolved spectra, all show a spectral hardening
in the second light-curve peak in GeV energies. Specifically, they
show an increase of the "cutoff energy" of a power-law spectral shape
in the second peak.
Considering the actual particle motion in the three-dimensional
pulsar magnetosphere, this work first explained this general behavior
of spectral hardening, as indicated by the lower panel. |