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Gamma-ray burst observations by Fermi Large Area Telescope revisited: new candidates found

Authors

  • G. I. Rubtsov,

    Corresponding author
    1. Institute for Nuclear Research of the Russian Academy of Sciences, 117312 Moscow, Russia
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  • M. S. Pshirkov,

    Corresponding author
    1. Universite Libre de Bruxelles, Service de Physique Theorique, CP225, 1050 Brussels, Belgium
    2. Pushchino Radio Astronomy Observatory, 142290 Pushchino, Russia
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  • P. G. Tinyakov

    Corresponding author
    1. Institute for Nuclear Research of the Russian Academy of Sciences, 117312 Moscow, Russia
    2. Universite Libre de Bruxelles, Service de Physique Theorique, CP225, 1050 Brussels, Belgium
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E-mail: grisha@ms2.inr.ac.ru (GIR); pshirkov@ulb.ac.be (MSP); petr.tiniakov@ulb.ac.be (PGT)

ABSTRACT

We search the Fermi Large Area Telescope (LAT) photon data base for an extended gamma-ray emission which could be associated with any of the 581 previously detected gamma-ray bursts (GRBs) visible to the Fermi-LAT. For this purpose, we compare the number of photons with energies E > 100 MeV and E > 1 GeV which arrived in the first 1500 s after the burst from the same region, to the expected background. We require that the expected number of false detections does not exceed 0.05 for the entire search and find the high-energy emission in 19 bursts, four of which (GRB 081009, GRB 090720B, GRB 100911 and GRB 100728A) were previously unreported. The first three are detected at energies above 100 MeV, while the last one shows a statistically significant signal only above 1 GeV.

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