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arXiv · 1601.01264

Modeling the early multiwavelength emission in GRB130427A

Nissim Fraija·William H. Lee·Péter Veres
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Abstract

One of the most powerful gamma-ray bursts, GRB 130427A was swiftly detected from GeV $γ$-rays to optical wavelengths. In the GeV band, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope observed the highest-energy photon ever recorded of 95 GeV, and a bright peak in the early phase followed by emission temporally extended for more than 20 hours. In the optical band, a bright flash with a magnitude of $7.03\pm 0.03$ in the time interval from 9.31 s to 19.31 s after the trigger was reported by RAPTOR in r-band. We study the origin of the GeV $γ$-ray emission, using the multiwavelength observation detected in X-ray and optical bands. The origin of the temporally extended LAT, X-ray and optical flux is naturally interpreted as synchrotron radiation and the 95-GeV photon and the integral flux upper limits placed by the HAWC observatory are consistent with synchrotron self-Compton from an adiabatic forward shock propagating into the stellar wind of its progenitor. The extreme LAT peak and the bright optical flash are explained through synchrotron self-Compton and synchrotron emission from the reverse shock, respectively, when the ejecta evolves in thick-shell regime and carries a significant magnetic field.

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Nissim Fraija, William H. Lee, Péter Veres. 2016-01-06. Modeling the early multiwavelength emission in GRB130427A. https://doi.org/10.3847/0004-637x%2F818%2F2%2F190

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