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Title: FERMI-LAT DETECTION OF PULSED GAMMA-RAYS ABOVE 50 GeV FROM THE VELA PULSAR

The first Fermi-Large Area Telescope (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 ∼10{sup –77}), we extracted its pulse profile using the Bayesian block algorithm and compared it with the distribution of the five observed photons above 50 GeV using the likelihood ratio test. Pulsation was significantly detected for photons above 50 GeV with a p-value of =3 × 10{sup –5} (4.2σ). The detection of pulsation is significant above 4σ at >79 GeV and above 3σ at >90 GeV energy bands, making this the highest energy pulsation significantly detected by the LAT. We explore the non-stationary outer gap scenario of the very high-energy emissions from the Vela pulsar.
Authors:
; ; ;  [1] ; ;  [2] ;  [3]
  1. Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong)
  2. Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China)
  3. Department of Astronomy and Space Science, Chungnam National University, Daejeon (Korea, Republic of)
Publication Date:
OSTI Identifier:
22364867
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 797; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALGORITHMS; COMPARATIVE EVALUATIONS; COSMIC PHOTONS; DETECTION; GAMMA RADIATION; GEV RANGE; PHOTON EMISSION; PULSARS; PULSATIONS; STARS; TELESCOPES