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arXiv · 2606.10519

Gamma-Ray Emission from the Crab Pulsar: A 17-Year Fermi-LAT Reanalysis

Liancheng Zhou·Yun-Lu Gong·Jun Fang·Li Zhang
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Abstract

We present a reanalysis of 17 years of Fermi Large Area Telescope (LAT) observations of the Crab pulsar obtained between 2008 August and 2025 August. Using monthly Jodrell Bank radio ephemerides, we assigned pulse phases to the LAT events and aligned the phase zero across the full data set. From this phase-aligned data set, we derived pulse profiles over 100 MeV to 300 GeV. The pulsed emission remains clearly detectable in the 10 to 20 GeV and 20 to 30 GeV bands, with H-test significances of 32.36 sigma and 11.59 sigma, respectively, but is not significantly detected in the 30 to 300 GeV band. Phase-resolved likelihood analysis was performed over 100 MeV to 30 GeV using 14 phase bins with comparable pulsed statistics. The fixed-window fractional fluxes show that the contribution of Peak 1 (P1) decreases steadily with energy, while those of Peak 2 (P2) and the Bridge increase, with P2 exceeding P1 above 10 GeV. Finally, the same phase-assignment framework also enables an off-pulse analysis from 100 MeV to 1 TeV, confirming the synchrotron and inverse-Compton components that dominate the emission in the selected off-pulse interval.

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Liancheng Zhou, Yun-Lu Gong, Jun Fang, Li Zhang. 2026-06-09. Gamma-Ray Emission from the Crab Pulsar: A 17-Year Fermi-LAT Reanalysis. https://arxiv.org/abs/2606.10519

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