On the Phase-Averaged Spectrum of Pulsars and Shape of Their Cutoffs

摘要

All gamma-ray pulsars exhibit an exponential cutoff in their spectra and for bright pulsars the statistics are sufficiently high to study the detailed shape of the cutoff. The phase-averaged spectra of some pulsars exhibit a sub-exponential cutoff, not predicted by any single physical mechanism. Further studies clarified that this gentler average cutoff is a consequence of having significant variations of the cutoff energy in the phase-resolved spectrum. In conclusion, the phase-averaged spectrum of a pulsar is not a physical quantity to test high-energy emission models.