A prompt extra component in the high energy spectrum of GRB 131108A

A. Giuliani; S. Mereghetti; M. Marisaldi; F. Longo; E. Del Monte; C. Pittori; F. Verrecchia; M. Tavani; P. Cattaneo; L. Pacciani; S. Vercellone; A. Rappoldi

arXiv · 1407.0238

A prompt extra component in the high energy spectrum of GRB 131108A

A. Giuliani·S. Mereghetti·M. Marisaldi·F. Longo·E. Del Monte·C. Pittori·F. Verrecchia·M. Tavani·P. Cattaneo·L. Pacciani·S. Vercellone·A. Rappoldi

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Abstract

The high-fluence GRB131108A at redshift z=2.4, was detected by the Mini-Calorimeter (MCAL, 0.35-100 MeV) and the Gamma- Ray Imaging Detector (GRID, 30 MeV - 30 GeV) onboard the AGILE satellite. The burst emission consisted of a very bright initial peak,lasting 0.1 s, followed by a fainter emission detected for ~25 s with the MCAL and ~80 s with the GRID. The AGILE spectra, when compared with those reported at lower energies, indicate the presence of a prominent high-energy component with peak energy in the 10-20 MeV region. Contrary to other GRBs, this high-energy component is present also during the initial peak, with power law photon index of about -1.6 below 10 MeV and -2.35+-0.2 above 30 MeV.

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A. Giuliani, S. Mereghetti, M. Marisaldi, F. Longo, E. Del Monte, C. Pittori, F. Verrecchia, M. Tavani, P. Cattaneo, L. Pacciani, S. Vercellone, A. Rappoldi. 2014-07-01. A prompt extra component in the high energy spectrum of GRB 131108A. https://arxiv.org/abs/1407.0238

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