Bright Gamma-Ray Flares Observed in GRB 131108A
Date Issued
2019
Author(s)
Ajello, M.
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Arimoto, M.
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Asano, K.
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Axelsson, M.
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Baldini, L.
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Barbiellini, G.
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Bastieri, D.
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Bellazzini, R.
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Berretta, A.
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Bissaldi, E.
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Blandford, R. D.
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Tajima, H.
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Takagi, K.
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Tak, D.
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Torres, D. F.
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Valverde, J.
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Wood, K.
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Yamazaki, R.
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Yassine, M.
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Zhu, S.
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Uhm, Z. Lucas
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Bonino, R.
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Zhang, Bing
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Bottacini, E.
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Bregeon, J.
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Bruel, P.
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Buehler, R.
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Buson, S.
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Cameron, R. A.
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Caputo, R.
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Caraveo, P. A.
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Cavazzuti, E.
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Chen, S.
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Chiaro, G.
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Ciprini, S.
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Costantin, D.
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Cutini, S.
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de la Torre Luque, P.
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de Palma, F.
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Di Lalla, N.
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Di Venere, L.
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Fana Dirirsa, F.
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Fegan, S. J.
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Franckowiak, A.
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Fukazawa, Y.
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Fusco, P.
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Gargano, F.
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Gasparrini, D.
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Giglietto, N.
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Giordano, F.
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•
Green, D.
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Grenier, I. A.
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Grondin, M. -H.
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Guiriec, S.
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Hays, E.
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Horan, D.
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Jóhannesson, G.
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Kocevski, D.
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Kovac'evic', M.
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Kuss, M.
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Larsson, S.
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Latronico, L.
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Li, J.
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Liodakis, I.
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Longo, F.
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Loparco, F.
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Lovellette, M. N.
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Lubrano, P.
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Maldera, S.
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Manfreda, A.
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Martí-Devesa, G.
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Mazziotta, M. N.
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McEnery, J. E.
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Mereu, I.
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Michelson, P. F.
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Mizuno, T.
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Monzani, M. E.
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Moretti, E.
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Morselli, A.
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Moskalenko, I. V.
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Negro, M.
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Nuss, E.
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Ohno, M.
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Omodei, N.
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Orlando, E.
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Palatiello, M.
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Paliya, V. S.
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Paneque, D.
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Pei, Z.
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Pesce-Rollins, M.
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Petrosian, V.
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Piron, F.
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Poon, H.
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Porter, T. A.
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Racusin, J. L.
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Rainò, S.
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Rando, R.
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Rani, B.
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Razzano, M.
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Reimer, A.
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Reimer, O.
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Serini, D.
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Sgrò, C.
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Siskind, E. J.
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Spandre, G.
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Spinelli, P.
Abstract
GRB 131108A is a bright long gamma-ray burst (GRB) detected by the Large Area Telescope and the Gamma-ray Burst Monitor on board the Fermi Gamma-ray Space Telescope. Dedicated temporal and spectral analyses reveal three γ-ray flares dominating above 100 MeV, which are not directly related to the prompt emission in the Gamma-ray Burst Monitor band (10 keV-10 MeV). The high-energy light curve of GRB 131108A (100 MeV-10 GeV) shows an unusual evolution: a steep decay, followed by three flares with an underlying emission, and then a long-lasting decay phase. The detailed analysis of the γ-ray flares finds that the three flares are 6-20 times brighter than the underlying emission and are similar to each other. The fluence of each flare, (1.6 ∼ 2.0) × 10-6 erg cm-2, is comparable to that of emission during the steep decay phase, 1.7 × 10-6 erg cm-2. The total fluence from three γ-ray flares is 5.3 × 10-6 erg cm-2. The three γ-ray flares show properties similar to the usual X-ray flares that are sharp flux increases, occurring in ∼50% of afterglows, in some cases well after the prompt emission. Also, the temporal and spectral indices during the early steep decay phase and the decaying phase of each flare show the consistency with a relation of the curvature effect (\hat{α } = 2 + \hat{β }), which is the first observational evidence of the high-latitude emission in the GeV energy band.
Volume
886
Issue
2
Start page
L33
Issn Identifier
2041-8205
Ads BibCode
2019ApJ...886L..33A
Rights
open.access
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