Fermi-LAT Detection of Pulsed Gamma-rays Above 50 GeV from the Vela Pulsar

Abstract

The First \fermi-LAT Catalog of Sources Above 10 GeV reported evidence of pulsed emission above 25 GeV from 12 pulsars, including the Vela pulsar, which showed evidence of pulsation at $>37$ GeV energy bands. Using 62 months of \fermi-LAT data, we analyzed the gamma-ray emission from the Vela pulsar and searched for pulsed emission above 50 GeV. Having confirmed the significance of the pulsation in 30-50 GeV with the H-test (p-value $\sim 10^{-77}$), we extracted its pulse profile using the Bayesian block algorithm and compared it with the distribution of the 5 observed photons above 50 GeV using the likelihood ratio test. Pulsation was significantly detected for photons above 50 GeV with p-value $=3\times 10^{-5}$ ($4.2\sigma$). The detection of pulsation is significant above $4\sigma$ at $>79$ GeV and above $3\sigma$ at $>90$ GeV energy bands, making this the highest energy pulsation significantly detected by the LAT. We explore non-stationary outer gap scenario of the very high-energy emissions from the Vela pulsar.

14 pages, 4figures, accepted by ApJ Letter

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Cited by in corpus (11)

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• A Search for Pulsations from Geminga Above 100 GeV with VERITAS
• A systematic synchro-curvature modelling of pulsar $\gamma$-ray spectra unveils hidden trends
• An assessment of the pulsar outer gap model. II: Implications for the predicted $\gamma$-ray spectra
• Gamma-ray emission from PSR J0007+7303 using 7 years of Fermi Large Area Telescope observations
• Prospects for the detection of high-energy (E>25 GeV) Fermi pulsars with the Cherenkov Telescope Array
• A Search for Pulsed Very High-Energy Gamma Rays from Thirteen Young Pulsars in Archival VERITAS Data
• Electric Field Screening with Back-Flow at Pulsar Polar Cap
• Rotationally-driven VHE emission from the Vela pulsar