2019年12月1日
Bright Gamma-Ray Flares Observed in GRB 131108A
Astrophysical Journal Letters
- 巻
- 886
- 号
- 2
- 記述言語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.3847/2041-8213/ab564f
© 2019. The American Astronomical Society. All rights reserved.. 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 (α = 2 + β ), which is the first observational evidence of the high-latitude emission in the GeV energy band.
- リンク情報
- ID情報
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- DOI : 10.3847/2041-8213/ab564f
- ISSN : 2041-8205
- eISSN : 2041-8213
- SCOPUS ID : 85077649318