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arXiv · 1312.2662

High energy emission of GRB 130821A: constraining the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow

Yun-Feng Liang·Bei Zhou·Hao-Ning He·Pak-Hin Thomas Tam·Yi-Zhong Fan·Da-Ming Wei
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Abstract

GRB 130821A was detected by Fermi-GBM/LAT, Konus-Wind, SPI-ACS/INTEGRAL, RHESSI and Mars Odyssey-HEND. Although the data of GRB 130821A are very limited, we show in this work that the high energy gamma-ray emission (i.e., above 100 MeV) alone imposes tight constraint on the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow. The temporal behavior of the high energy gamma-ray emission is consistent with the forward shock synchrotron radiation model and the circum-burst medium likely has a constant-density profile. The Lorentz factor is about a few hundred, similar to other bright GRBs.

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Yun-Feng Liang, Bei Zhou, Hao-Ning He, Pak-Hin Thomas Tam, Yi-Zhong Fan, Da-Ming Wei. 2013-12-10. High energy emission of GRB 130821A: constraining the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow. https://doi.org/10.1088/0004-637x/781/2/74

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